Hermetic terminal for an aimd having a composite brazed conductive lead

ABSTRACT

An insulative feedthrough attachable to an active implantable medical device includes a feedthrough body having a material which is both electrically insulative, biocompatible and separates a body fluid side from a device side. A passageway is disposed through the feedthrough body. A composite conductor is disposed within the passageway and has a body fluid side metallic wire electrically conductive to a device side metallic wire. The body fluid side metallic wire extends from a first end disposed inside the passageway to a second end on the body fluid side. The device side metallic wire extends from a first end disposed inside the passageway to a second end on the device side. The body fluid side metallic wire is hermetically sealed to the feedthrough body. The body fluid side metallic wire is biocompatible and is not the same material as the device side metallic wire.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority to provisionalpatent application 62/418,834 filed on Nov. 8, 2016 the entire contentsof which are fully incorporated herein with these references.

FIELD OF THE INVENTION

The present invention generally relates to implantable medical devicesand hermetic terminal subassemblies. More particularly, the presentinvention relates a hermetic terminal having a composite conductive leadbrazed into an insulator body.

BACKGROUND OF THE INVENTION

A wide assortment of active implantable medical devices (AIMDs) arepresently known and in commercial use. Such devices include cardiacpacemakers, cardiac defibrillators, cardioverters, neurostimulators, andother devices for delivering and/or receiving electrical signals to/froma portion of the body. Sensing and/or stimulating leads extend from theassociated implantable medical device to a distal tip electrode orelectrodes in contact with body tissue.

The hermetic terminal or feedthrough of these implantable devices isconsidered critical. Hermetic terminals or feedthroughs are generallywell-known in the art for connecting electrical signals through thehousing or case of an AIMD. For example, in implantable medical devicessuch as cardiac pacemakers, implantable cardioverter defibrillators, andthe like, a hermetic terminal comprises one or more conductive pathwayswhich may include conductive terminal pins, conductive filled vias,leadwires and the like supported by an insulative structure forfeedthrough passage from the exterior to the interior of an AIMDelectromagnetic shield housing. Hermetic terminals or feedthroughs forAIMDs must be biocompatible as well as resistant to degradation underapplied bias current or voltage (biostable). Hermeticity of thefeedthrough is imparted by judicious material selection and carefullyprescribed manufacturing processing. Sustainable hermeticity of thefeedthrough over the lifetime of these implantable devices is criticalbecause the hermetic terminal intentionally isolates the internalcircuitry and components of the device (AIMD) from the external bodyfluid environment to which the component is exposed. In particular, thehermetic terminal isolates the internal circuitry, connections, powersources and other components in the device from ingress of body fluids.Ingress of body fluids into an implantable medical device is known to bea contributing factor to device malfunction and may contribute to thecompromise or failure of electrical circuitry, connections, powersources and other components within an implantable medical device thatare necessary for consistent and reliable device therapy delivery to apatient. Furthermore, ingress of body fluids may compromise animplantable medical device's functionality which may constituteelectrical shorting, element or joint corrosion, metal migration orother such harmful consequences affecting consistent and reliable devicetherapy delivery.

In addition to concerns relative to sustained terminal or feedthroughhermeticity, other potentially compromising conditions must beaddressed, particularly when a hermetic terminal or feedthrough isincorporated within an implantable medical device. For example, thehermetic terminal or feedthrough pins are typically connected to one ormore lead conductors of implantable therapy delivery leads. Theseimplantable therapy delivery leads can effectively act as antennas thatreceive electromagnetic interference (EMI) signals. Therefore, whenthese electromagnetic signals enter within the interior space of ahermetic implantable medical device, facilitated by the therapy deliveryleads, they can negatively impact the intended function of the medicaldevice and as a result, negatively impact therapy delivery intended fora patient by that device. EMI engineers commonly refer to this as the“genie in the bottle” effect. In other words, once the genie (i.e., EMI)is inside the hermetic housing of the device, it can wreak havoc withelectronic circuit functions by cross-coupling and re-radiating withinthe device.

Another particularly problematic condition associated with implantedtherapy delivery leads occurs when a patient is in an MRI environment.In this case, the MRI RF electrical currents imposed on the implantedtherapy delivery leads can cause the leads to heat to the point wheretissue damage is likely. Moreover, MRI induced RF currents(electromagnetic interference—EMI) may be coupled to implanted therapydelivery leads resulting in undesirable electrical currents which canenter the AIMD and can disrupt or damage the sensitive electronicswithin the implantable medical device.

Therefore, materials selection and fabrication processing parameters areof utmost importance in creating a hermetic terminal (or feedthrough) ora structure embodying a hermetic terminal (or feedthrough), that cansurvive anticipated and possibly catastrophically damaging environmentalconditions and that can be practically and cost effectivelymanufactured.

In general, hermetic terminal subassemblies for AIMDs comprise atitanium ferrule and a gold brazed alumina insulator. Alternatively,hermetic terminals may comprise a ferrule and a compression or fusionglass seal. Hermetic terminals or feedthrough assemblies utilizingceramic dielectric materials may fail in a brittle manner. A brittlefailure typically occurs when the ceramic structure is deformedelastically up to an intolerable stress, at which point the ceramicfails catastrophically. Most brittle failures occur by crack propagationin a tensile stress field. Even microcracking caused by sufficientlyhigh tensile stress concentrations may result in a catastrophic failureincluding loss of hermeticity identified as critical in hermeticterminals for implantable medical devices. Loss of hermeticity may be aresult of design aspects such as a sharp corner which creates a stressriser, mating materials with a difference of coefficient of thermalexpansions (CTE) that generate tensile stresses that ultimately resultin loss of hermeticity of the feedthrough or interconnect structure.

In the specific case of hermetic terminal or feedthrough designs, atensile stress limit for a given ceramic based hermetic design structurecannot be specified because failure stress in these structures is not aconstant. As indicated above, variables affecting stress levels includethe design itself, the materials selection, symmetry of the feedthrough,and the bonding characteristics of mating surfaces within thefeedthrough. Hence, length, width and height of the overall ceramicstructure matters as do the number, spacing, length and diameter of theconductive pathways (vias, terminal pins, leadwires, etc.) in thatstructure. The selection of the mating materials, that is, the materialthat fills the vias (or leadwire) and the material that forms the baseceramic, are important. Finally, the fabrication processing parameters,particularly at binder burnout, sintering and cool down, make adifference. When high reliability is required in an application such asindicated with hermetic terminals or feedthroughs for AIMDs, to provideinsurance for a very low probability of failure it is necessary todesign a hermetic terminal assembly or feedthrough structure so thatstresses imparted by design, materials and/or processing are limited toa smaller level of an average possible failure stress. Further, toprovide insurance for a very low probability of failure in a criticalceramic based assembly or subassembly having sustainable hermeticrequirements, it is also necessary to design structures embodying ahermetic terminal or feedthrough such that stresses in the finalassembly or subassembly are limited to a smaller level of an averagepossible failure stress for the entire assembly or subassembly. Inhermetic terminals and structures comprising hermetic terminals forAIMDs wherein the demand for biocompatibility exists, this task becomeseven more difficult.

The most critical feature of a feedthrough design or any terminalsubassembly is the metal/ceramic interface within the feedthrough thatestablishes the hermetic seal. One embodiment of the present inventiontherefore provides where a hermetic feedthrough comprising a monolithicalumina insulator substrate within which a platinum, palladium or thelike conductive pathway or via resides or wherein a metallic leadwire(terminal pin) resides. More specifically in the case of a filled via,the present invention provides a hermetic feedthrough in which thehermetic seal is created through the intimate bonding of a CERMET(ceramic metal) or a platinum metal residing within the aluminasubstrate.

A traditional ceramic-to-metal hermetic terminal is an assembly of threecomponents: electrical conductors (leadwires, pins, terminal pins,filled vias) that conduct electrical current, a ceramic insulator, and ametal housing, which is referred to as the flange or the ferrule (oreven the AIMD housing itself). Brazed joints typically hermetically sealthe metal leadwires and the flange or ferrule to the ceramic insulator.For a braze-bonded joint, the braze material is generally intended todeform in a ductile manner in order to compensate for perturbations thatstress the bond between the mating materials as the braze material mayprovide ductile strain relief when the thermal expansion mismatchbetween the ceramic and metal is large. Thus, mating materials withlarge mismatches in CTE can be coupled through braze materials whosehigh creep rate and low yield strength reduce the stresses generated bythe differential contraction existing between these mating materials.Glass seals are also known in the art, which form a hermetic seal to theferrule and one or more leadwires passing through the glass seal.

Regarding EMI, a terminal or feedthrough capacitor EMI filter may bedisposed at, near or within a hermetic terminal or feedthrough resultingin a feedthrough filter capacitor which diverts high frequencyelectrical signals from lead conductors to the housing or case of anAIMD. Many different insulator structures and related mounting methodsare known in the art for use of feedthrough capacitor EMI filters inAIMDs, wherein the insulative structure also provides a hermeticterminal or feedthrough to prevent entry of body fluids into the housingof an AIMD. In the prior art devices, the hermetic terminal subassemblyhas been combined in various ways with a ceramic feedthrough filter EMIcapacitor to decouple interference signals to the housing of the medicaldevice.

In a typical prior art unipolar construction (as described in U.S. Pat.No. 5,333,095 and herein incorporated by reference), a round/discoidal(or rectangular) ceramic feedthrough EMI filter capacitor is combinedwith a hermetic terminal pin assembly to suppress and decouple undesiredinterference or noise transmission along a terminal pin. The feedthroughcapacitor is coaxial having two sets of electrode plates embedded inspaced relation within an insulative dielectric substrate or base,formed typically as a ceramic monolithic structure. One set of theelectrode plates are electrically connected at an inner diametercylindrical surface of the coaxial capacitor structure to the conductiveterminal pin utilized to pass the desired electrical signal or signals.The other or second set of electrode plates are coupled at an outerdiameter surface of the round/discoidal capacitor to a cylindricalferrule of conductive material, wherein the ferrule is electricallyconnected in turn to the conductive housing of the electronic device.The number and dielectric thickness spacing of the electrode plate setsvaries in accordance with the capacitance value and the voltage ratingof the coaxial capacitor. The outer feedthrough capacitor electrodeplate sets (or “ground” plates) are coupled in parallel together by ametalized layer which is fired, sputtered or plated onto the ceramiccapacitor. This metalized band, in turn, is coupled to the ferrule byconductive adhesive, soldering, brazing, welding, or the like. The innerfeedthrough capacitor electrode plate sets (or “active” plates) arecoupled in parallel together by a metalized layer which is either glassfrit fired or plated onto the ceramic capacitor. This metalized band, inturn, is mechanically and electrically coupled to the lead wire(s) byconductive adhesive, soldering, or the like. In operation, the coaxialcapacitor permits passage of relatively low frequency biologic signalsalong the terminal pin, while shielding and decoupling/attenuatingundesired interference signals of typically high frequency to the AIMDconductive housing. Feedthrough capacitors of this general type areavailable in unipolar (one), bipolar (two), tripolar (three), quadpolar(four), pentapolar (five), hexpolar (6) and additional leadconfigurations. The feedthrough capacitors (in both discoidal andrectangular configurations) of this general type are commonly employedin implantable cardiac pacemakers and defibrillators and the like,wherein the pacemaker housing is constructed from a biocompatible metalsuch as titanium alloy, which is electrically and mechanically coupledto the ferrule of the hermetic terminal pin assembly which is in turnelectrically coupled to the coaxial feedthrough filter capacitor. As aresult, the filter capacitor and terminal pin assembly prevents entranceof interference signals to the interior of the pacemaker housing,wherein such interference signals could otherwise adversely affect thedesired cardiac pacing or defibrillation function.

Therefore, it is very common in the prior art to construct a hermeticterminal subassembly with a feedthrough capacitor attached near theinside of the AIMD housing on the device side. The feedthrough capacitordoes not have to be made from biocompatible materials because it islocated on the device side inside the AND housing. The hermetic terminalsubassembly includes conductive pathways (leadwires, pins, terminalpins, filled vias, etc.) to hermetically pass through the insulator innon-conductive relation with the ferrule or the AIMD housing. Theconductive pathways also pass through the feedthrough hole of thecapacitor to electronic circuits disposed inside of the AIMD housing.These leadwires are typically electrically continuous and, on the bodyfluid side, must be biocompatible and non-toxic. Generally, theseconductive pathways are constructed of platinum or platinum-iridium,palladium or palladium-iridium, niobium pins or filled vias withconductive powders, ceramics, gradient materials or the like.Platinum-iridium is an ideal choice because it is biocompatible,non-toxic and is also mechanically very strong. The iridium is added toenhance material stiffness and to enable the hermetic terminalsubassembly leadwire to sustain bending stresses. An issue with the useof platinum for leadwires is that platinum has become extremelyexpensive and may be subject to premature fracture under rigorousprocessing such as ultrasonic cleaning or application use/misuse,possibly unintentional damaging forces resulting from Twiddler'sSyndrome. Twiddler's Syndrome is a situation documented in theliterature where a patient will unconsciously or knowingly twist theimplantable device to the point where attached leads may even fracture.

Accordingly, what is needed is a is a hermetic seal subassembly whichhas a biocompatible and non-toxic lead or leadwire on the body fluidside, which is co-joined within the hermetic seal insulator to a lowercost device side lead, which may be routed to AIMD internal electroniccircuits. The present invention does not change the way the prior artleadwires are generally connected to a body fluid side header block orimplantable lead. The present invention also does not change the waythat leadwires may be routed inside the device and connected directly toan AIMD electronic circuit board or to an intermediate flex cable or thelike. Accordingly, what is needed is a way to provide a body fluid sidebiocompatible leadwire, which is joined within the hermetic sealinsulator to a lower cost leadwire or pin. As will be seen, this notonly saves a much lower cost hermetic seal subassembly, but alsofacilitates automation; for example, to add a feedthrough capacitorfilter or a circuit board type of EMI filter.

SUMMARY OF THE INVENTION

In an exemplary embodiment of the present invention a hermeticallysealed feedthrough subassembly is attachable to an active implantablemedical device (AIMD), the feedthrough subassembly comprising: (a) aninsulator substrate assembly, comprising: i) an insulator body definedas having a first insulator side opposite a second insulator side, thefirst insulator side and second insulator side separated and connectedby at least one outside surface; ii) at least one via hole disposedthrough the insulator body extending from the first insulator side tothe second insulator side; iii) an internal metallization formed atleast partially on an inside of the at least one via hole; iv) a firstconductive leadwire having a first conductive leadwire first end atleast partially disposed within the at least one via hole and having afirst conductive leadwire second end disposed past the first insulatorside; v) a second conductive leadwire having a second conductiveleadwire first end at least partially disposed within the at least onevia hole and having a second conductive leadwire second end disposedpast the second insulator side; vi) wherein the first conductiveleadwire first end is disposed near, at or adjacent to the secondconductive leadwire first end; vii) wherein the first conductiveleadwire is not the same material as the second conductive leadwire;viii) a first braze at least partially between the first conductiveleadwire first end, the second conductive leadwire first end and theinternal metallization, the first braze forming a first hermetic sealseparating the first insulator side from the second insulator side; andix) an external metallization disposed at least partially on the atleast one outside surface of the insulator body; and (b) a ferrule,comprising: i) a conductive ferrule body defined as having a firstferrule side opposite a second ferrule side and defining a ferruleopening between and through the first and second ferrule sides, whereinthe insulator body is at least partially disposed within the ferruleopening; ii) a second braze at least partially between the externalmetallization of the insulator body and the conductive ferrule body, thesecond braze forming a second hermetic seal hermetically sealing theferrule opening.

Other exemplary embodiments may include a feedthrough filter capacitordisposed on the second insulator side, the feedthrough filter capacitorcomprising: i) at least one active electrode plate disposed parallel andspaced from at least one ground electrode plate, wherein the plates aredisposed within a capacitor dielectric substrate; ii) a first passagewaydisposed through the capacitor dielectric substrate and disposedperpendicular to the plates; iii) a capacitor internal metallizationdisposed within the first passageway electrically connected to the atleast one active electrode plate and in non-conductive relation with theat least one ground electrode plate; iv) a capacitor externalmetallization disposed on an outside surface of the capacitor dielectricsubstrate and electrically connected to the at least one groundelectrode plate and in non-conductive relation with the at least oneactive electrode plate.

Other exemplary embodiments may include a third conductive leadwirehaving a third conductive leadwire first end at least partially disposedwithin the first passageway of the feedthrough filter capacitor andhaving a third conductive leadwire second end disposed past thefeedthrough filter capacitor configured to be connectable to electronicsinternal to the AIMD, wherein the second conductive leadwire second endis at least partially disposed within the first passageway of thefeedthrough filter capacitor, wherein the second conductive leadwiresecond end is at, near or adjacent to the third conductive leadwirefirst end.

Other exemplary embodiments may include a first electrically conductivematerial forming at least a three-way electrical connection electricallyconnecting the second conductive leadwire second end, the thirdconductive leadwire first end and the capacitor internal metallization.

The first electrically conductive material may be selected from thegroup consisting of a solder, a solder BGA, a solder paste, an epoxy,and a polyimide.

Other exemplary embodiments may include a second electrically conductivematerial electrically connecting the capacitor external metallization tothe ferrule and/or to the second braze.

Other exemplary embodiments may include at least one internal groundplate disposed within the insulator body electrically connecting theinternal metallization formed at least partially on the inside of the atleast one via hole to the external metallization disposed at leastpartially on the at least one outside surface of the insulator body.

The first braze and second braze may be formed at the same time and areconnected by a braze channel.

A conductive clip may be electrically coupled between and to the secondconductive leadwire and the ferrule.

The ferrule may include a conductive peninsula extending at leastpartially into the ferrule opening, wherein the second conductiveleadwire is electrically coupled to the conductive peninsula with thefirst braze.

Other exemplary embodiments may include a chip capacitor disposed on thesecond insulator side, the chip capacitor comprising: i) at least oneactive electrode plate disposed parallel and spaced from at least oneground electrode plate, wherein the plates are disposed within acapacitor dielectric substrate; ii) a first capacitor metallizationdisposed on one end of the chip capacitor and electrically connected tothe at least one active electrode plate and in non-conductive relationwith the at least one ground electrode plate; iii) a second capacitormetallization disposed on another end of the chip capacitor andelectrically connected to the at least one ground electrode plate and innon-conductive relation with the at least one active electrode plate.

Other exemplary embodiments may include a first electrically conductivematerial electrically coupling the first capacitor metallization to thesecond conductive leadwire.

Other exemplary embodiments may include a second electrically conductivematerial electrically coupling the second capacitor metallization to theferrule and/or the second gold braze.

The chip capacitor may be attached to the insulator body. Alternatively,the chip capacitor may be attached to a circuit board, wherein thecircuit board is attached to the insulator body.

Other exemplary embodiments may include an oxide-resistant metaladdition, wherein a second electrically conductive material electricallycouples the second capacitor metallization to the oxide resistant metaladdition, and wherein a third electrically conductive materialelectrically connects the oxide-resistant metal addition to the ferruleor wherein the oxide-resistant metal addition is welded to the ferrule.

The second conductive leadwire may comprise platinum or palladium.

The first conductive leadwire may comprise niobium or tantalum.

The first braze and second braze may each comprise a gold braze. Thefirst braze may be disposed at or near the second insulator side anddoes not extend to at or near the first insulator side. The first brazemay be disposed at or near the first insulator side and may not extendto at or near the second insulator side.

The third conductive leadwire first end may be pre-tinned.

The first and second hermetic seals may have a leak rate no greater than1×10⁻⁷ std cc He/sec.

The external metallization may be disposed at least partially on the atleast one outside surface of the insulator body comprises an adhesionmetallization and a wetting metallization, wherein the adhesionmetallization may be disposed at least partially on the at least oneoutside surface of the insulator body and wherein the wettingmetallization may be disposed on the adhesion metallization.

Other exemplary embodiments may include an insulative washer which maybe disposed between the insulator substrate assembly and the feedthroughfilter capacitor.

The ferrule may be configured to be joined to an AIMD housing by a laserweld or braze.

The ferrule may be formed from and as a continuous part of an AIMDhousing.

The first insulator side may be a body fluid side and the secondinsulator side may be a device side.

In another exemplary embodiment of the present invention, an insulativefeedthrough attachable to an active implantable medical device,comprises: a feedthrough body comprising a material which is bothelectrically insulative and biocompatible, wherein the feedthrough bodyis configured to be hermetically installed within the active implantablemedical device separating a body fluid side from a device side; apassageway disposed through the feedthrough body extending from the bodyfluid side to the device side; a composite conductor disposed within thepassageway, the composite conductor comprising a body fluid sidemetallic wire electrically conductive to a device side metallic wire;

wherein the body fluid side metallic wire extends from a first enddisposed inside the passageway to a second end on the body fluid side;wherein the device side metallic wire extends from a first end disposedinside the passageway to a second end on the device side; wherein thebody fluid side metallic wire is hermetically sealed to the feedthroughbody; wherein the body fluid side metallic wire is biocompatible; andwherein the body fluid side metallic wire is not the same material asthe device side metallic wire.

The ferrule may be made from an electrically conductive material, theferrule configured to be hermetically sealed to a housing of theimplantable medical device, wherein the ferrule defines a ferruleopening and the feedthrough body is hermetically sealed to the ferruleclosing the ferrule opening. The ferrule may comprise titanium.

An adhesion layer may be disposed on an outside surface of thefeedthrough body, a wetting layer may be disposed on the adhesion layer,and a gold braze may be hermetically sealing the wetting layer to theferrule.

The ferrule opening may define an inner ferrule surface, wherein thefeedthrough body is at least partially disposed within ferrule openingand hermetically sealed by the gold braze to the ferrule inner surface.

The device side metallic wire may not biocompatible. The device sidemetallic wire may be platinum. The device side metallic wire comprisingplatinum may not include iridium.

The second end of the body fluid side metallic wire may extend past thefeedthrough body on the body fluid side. The second end of the deviceside metallic wire may extend past the feedthrough body on the deviceside.

The second end of the body fluid side metallic wire may be aligned witha body fluid side surface of the feedthrough body. The second end of thedevice side metallic wire may be aligned with a device side surface ofthe feedthrough body.

The second end of the body fluid side metallic wire may be recessed froma body fluid side surface of the feedthrough body. The second end of thedevice side metallic wire may be recessed from a device side surface ofthe feedthrough body.

The first end of the body fluid side metallic wire may be soldered orwelded to the first end of the device side metallic wire.

An adhesion layer may be disposed on an inside surface of thepassageway, a wetting layer may be disposed on the adhesion layer, and agold braze may hermetically seal the wetting layer to the body fluidside metallic wire.

The gold braze may be connected to the device side metallic wire.

A capacitor may be disposed on the device side of the feedthrough body,wherein the capacitor comprises at least one active electrode plate andat least one ground electrode plate disposed within a capacitordielectric, wherein an active end metallization is electricallyconnected to the at least one active electrode plate and a ground endmetallization is electrically connected to the at least one groundelectrode plate. The active end metallization may be in electricalcommunication with the device side metallic wire, and wherein the groundend metallization may be in electrical communication with the ferrule.

The capacitor may be a chip capacitor. The chip capacitor may be mountedto the feedthrough body. The chip capacitor may be mounted to a circuitboard, wherein the circuit board is mounted to the feedthrough body.

The capacitor may be a feedthrough capacitor. The capacitor may bemounted to an adhesive washer and the adhesive washer is mounted to thefeedthrough body.

The second end of the device side metallic wire may extend past thefeedthrough body on the device side and is disposed within a metallizedvia formed through the feedthrough capacitor, wherein the metallizationof the metallized via comprises the active end metallization.

A third wire may be disposed on the device side and extending at leastpartially into the metallized via.

A conductive material may be electrically connected to the second end ofthe device side metallic wire, to the third wire and to the active endmetallization of the capacitor.

An internally grounded capacitor may be disposed on the device side ofthe feedthrough body, wherein the capacitor comprises at least oneactive electrode plate and at least one ground electrode plate disposedwithin a capacitor dielectric, wherein an active end metallization iselectrically connected to the at least one active electrode plate and aground end metallization is electrically connected to the at least oneground electrode plate, wherein the active end metallization is formedwithin an active via disposed through the capacitor dielectric and theground end metallization is formed within a ground via disposed throughthe capacitor, wherein the capacitor does not have an externalmetallization on an outside surface of the capacitor dielectric.

The feedthrough body may comprise a conductive pathway in electricalcommunication with the ferrule on one end of the conductive pathway andin electrical communication with the ground end metallization on theother end of the electrical pathway. The conductive pathway may comprisea gold braze. The gold braze may also hermetically seals the feedthroughbody to the ferrule.

The conductive pathway may comprise at least one conductive groundinglayer disposed with the feedthrough body.

A conductive pin may be in electrical communication to the ground endmetallization on one end of the conductive pin and in electricalcommunication with the conductive pathway on the other end of theconductive pin.

A ferrule may be made from a conductive material, the ferrule configuredto be hermetically sealed to a housing of the implantable medicaldevice, wherein the ferrule defines a ferrule opening and thefeedthrough body is hermetically sealed to the ferrule closing theferrule opening; including a feedthrough capacitor disposed on thedevice side of the feedthrough body, wherein the capacitor comprises atleast one active electrode plate and at least one ground electrode platedisposed within a capacitor dielectric, wherein an active endmetallization is electrically connected to the at least one activeelectrode plate and a ground end metallization is electrically connectedto the at least one ground electrode plate; including a gold brazeattached to the ferrule on the device side; and including anelectrically conductive fill connecting the ground end metallization tothe gold braze.

The feedthrough body may comprise a glass insulator, wherein thehermetic seal between the feedthrough body and the ferrule is formed atthe same time as the hermetic seal between the composite conductor andthe feedthrough body. An alumina washer disposed over the feedthroughbody on the body fluid side.

Other features and advantages of the present invention will becomeapparent from the following more detailed description, when taken inconjunction with the accompanying drawings, which illustrate, by way ofexample, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a wire-formed diagram of a generic human body showing a numberof exemplary implantable medical devices;

FIG. 2 is a side view of a prior art cardiac pacemaker;

FIG. 3A is a perspective partial cutaway view of a unipolar capacitor;

FIG. 3B is a side sectional view of a similar unipolar capacitor of FIG.3A now mounted to a hermetic feedthrough for an active implantablemedical device;

FIG. 3C is an electrical schematic representation of the unipolarfiltered feedthrough assembly previously illustrated in FIG. 3B;

FIG. 3D is generally taken along lines 3D-3D from FIG. 3A and is anexploded perspective view of the electrode layer stack up;

FIG. 4A is a perspective view of a quadpolar feedthrough capacitor andhermetic terminal assembly;

FIG. 4B is a sectional view of the feedthrough and hermetic terminalassembly of FIG. 4A taken along lines 4B-4B;

FIG. 4C is an electrical schematic representation of the quadpolarfiltered feedthrough assembly as previously illustrated in FIGS. 4A and4B;

FIG. 4D is an exploded perspective view of the electrode layer stack upof the structure of FIGS. 4A and 4B;

FIG. 5 illustrates an exploded perspective view of an internallygrounded prior art feedthrough capacitor;

FIG. 6 illustrates the structure of FIG. 5 where now the capacitor isformed as a monolithic structure;

FIG. 7 illustrates the structure of FIG. 6 fully assembled into afeedthrough filtered hermetic terminal;

FIG. 7A is the electrical schematic for the feedthrough filteredhermetic terminal previously described in FIGS. 5, 6 and 7;

FIG. 8 is a sectional view of an exemplary filtered feedthrough of thepresent invention now showing an additional leadwire portion connectedin shear between both the insulator of the hermetic feedthrough and theinternal metallized hole of the capacitor;

FIG. 8A is similar to FIG. 8 now showing the capacitor captured with theferrule and a polyimide covering disposed over the capacitor on thedevice side;

FIG. 8B is similar to FIG. 8 now showing the insulator captured withinthe ferrule by a cermet;

FIG. 8C is similar to FIG. 8 now showing a toroidal-shaped ferrule;

FIG. 8D is similar to FIG. 8 now showing the insulator as a glass whichis hermetically sealed to the lead wires and ferrule at the same time;

FIG. 8E is similar to FIG. 8 now showing the capacitor outsidemetallization electrically coupled to the ferrule through a second goldbraze separate from the gold braze hermetically sealing the insulator tothe ferrule;

FIG. 8F is similar to FIG. 8 now showing both the insulator and theferrule are centered by at least partially disposing them within theferrule;

FIG. 9 is an exploded sectional view of the structure of FIG. 8 nowshown upside-down for better understanding of the manufacturing steps;

FIG. 10 illustrates the completed assembly of FIG. 9 prior to reflowingthe solder preform;

FIG. 11 is very similar to FIG. 8 except on the capacitor device sidecounter-bores are shown instead of counter-sinks;

FIG. 12 is very similar to FIG. 8, except that the counter-sinks havebeen eliminated on both the right and the left side of the device sideof the feedthrough capacitor;

FIG. 13 is very similar to FIG. 8, except that in this case thecounter-bores on the device side of the hermetic insulator have beenreplaced by counter-sinks;

FIG. 14 is very similar to FIG. 8, except that the counter-bores in thealumina ceramic insulator 188 have been removed;

FIG. 15 is very similar to FIG. 8, except that the body fluid sideleadwires have been replaced by biostable and biocompatible wire bondpads;

FIG. 16 illustrates an alternate method of manufacturing a nail-headedlead as previously described in FIG. 15;

FIG. 17 illustrates that the nail head may be modified to have anelongated piece that engages the gold braze preform;

FIG. 18 illustrates that a counter-bore may be included within themachine nail head into which the lead protrudes;

FIG. 19 is very similar to FIG. 18, except that in this case, thecounter-bore and nail head is smaller and that a protrusion or extensionis formed on the end of lead to engage counter-bore;

FIG. 20 illustrates that the nail head may have a semi-circular (orother) shape;

FIG. 21 illustrates that the contact area can be further increased byusing a larger gold preform in comparison to FIG. 20;

FIG. 22 is very similar to FIG. 8, except now the insulator ishermetically sealed to the active implantable medical device housingthereby eliminating the ferrule;

FIG. 23 is the same as FIG. 8, except that the low cost leadwires,instead of being stranded, are solid wire stubs;

FIG. 24 is similar to FIG. 8, but now shows a gold braze moatelectrically coupling the internal ground pin and the ferrule;

FIG. 24A is one possible schematic diagram of the filtered feedthroughassembly of FIG. 24;

FIG. 24B is almost the same as FIG. 24, except the body fluid sideground lead has been eliminated;

FIG. 24C is a perspective view of a green ceramic bar illustrating thatfour hermetic insulators are disposed on the bar;

FIG. 24D is a top view of the device side of the green ceramic bar ofFIG. 24C;

FIG. 24E is a top view of the body fluid side of the green ceramic barof FIG. 24C;

FIG. 24F is a perspective sectional view taken along lines 24F-24F ofFIG. 24D;

FIG. 24G is a perspective sectional view taken along lines 24G-24G ofFIG. 24D;

FIG. 24H is a perspective similar to FIG. 24C now showing the fourhermetic insulators being partially cut from the bar;

FIG. 24I is a perspective view of the body fluid side of an insulator ofthe present invention;

FIG. 24J is a perspective view of the device side of the insulator ofFIG. 24I;

FIG. 24K is very similar to FIG. 24J, but illustrates that more than oneslot can be used;

FIG. 24L illustrates the insulator structure of FIG. 24I and FIG. 24J,partially placed into, within or onto a ferrule;

FIG. 24M is a sectional view taken from section 24M-24M from FIG. 24Lillustrating the grounding slot in cross-section which comprises a goldbraze;

FIG. 24N illustrates the hermetic seal subassembly of FIG. 24 invertedand rotated;

FIG. 24O is a sectional view taken from section 24O-24O from FIG. 24Nillustrating the novel grounding slot in cross-section;

FIG. 24P illustrates an internally grounded capacitor mounted to thehermetic seal subassembly previously illustrated in FIGS. 24N and 24O;

FIG. 24Q is taken from section 24Q-24Q from FIG. 24P illustrating anenlarged view of the internally grounded capacitor's ground connectionto the gold braze grounding slot;

FIG. 24R is an exploded view taken from FIG. 24P illustrating that theBGA connection may be dispensed by a robot;

FIG. 24S is similar to FIGS. 24P and 24R, except in this case, insteadof a gold braze slot, a peninsula structure, which is very similar tothat described in FIG. 6, is shown;

FIG. 24T is similar to MG. 24S, except now the ferrule is connected tothe housing of the active implantable medical device and the capacitoris being mounted to the ferrule and insulator surfaces;

FIG. 24U is the schematic diagram of the internally grounded capacitorwhich was taught in FIG. 24C to FIG. 24T;

FIG. 25 illustrates an internally grounded feedthrough capacitor aspreviously described in FIG. 24, except that the gold braze moat hasbeen replaced by internal ground plates that are embedded within amultilayer and co-fired insulator;

FIG. 26 illustrates the assembly steps for the structure of FIG. 25 in amanner very similar to that previously described in FIG. 9;

FIG. 27 illustrates the exploded components of FIG. 26 after thecapacitor has been adhesively bonded to the hermetic seal insulator andferrule;

FIG. 28 is another internally grounded capacitor similar to thosepreviously described in FIG. 24 and FIG. 25 where now the gold brazemoat of FIG. 24 has been largely replaced with a metallic piece;

FIG. 29 is a perspective view of the metallic piece from FIG. 28;

FIG. 30 is another internally grounded capacitor version similar toFIGS. 25 and 28 where now the ferrule has been extended into a peninsulaand electrically coupled to the ground lead;

FIG. 30A is similar to FIG. 40, except that the device side leads havebeen extended below the surface of an internally grounded feedthroughcapacitor such that a flex cable can be attached;

FIG. 30B is similar to FIG. 30A, except that in this case the leadwireshave been elongated such that they can be routed all the way to an AIMDcircuit board;

FIG. 31 illustrates a prior art monolithic ceramic capacitor;

FIG. 32 illustrates a cross-section of an MLCC capacitor of FIG. 31taken along lines 32-32;

FIG. 33 illustrates a cross-section of the MLCC capacitor of FIG. 32taken along lines 33-33;

FIG. 34 illustrates a cross-section of the MLCC capacitor of FIG. 32taken along lines 34-34;

FIG. 35 illustrates a bipolar prior art applications of MLCC capacitorsto active implantable medical device applications;

FIG. 35A illustrates a unipolar prior art applications of MLCCcapacitors to active implantable medical device applications;

FIG. 35B illustrates a top view of the structure of FIG. 35A;

FIG. 35C illustrates a prior art flat-thru capacitor;

FIG. 35D illustrates the electrode plates of the flat-thru capacitor ofFIG. 35C;

FIG. 35E illustrate a perspective view of a three-terminal capacitorthat is also known in the industry as X2Y attenuator;

FIG. 35F is another perspective view of the structure of FIG. 35E;

FIG. 35G is the electrical schematic for FIGS. 35E and 35F;

FIG. 36 is a sectional view and illustrates the application of MLCCcapacitors to the present invention;

FIG. 37 illustrates a modified hermetic terminal similar to FIG. 36where now the gold braze is disposed towards the body fluid side insteadof towards the device side and therefore an oxide-resistant metaladdition is used;

FIG. 38 is one exemplary possible electrical schematic of the overallfiltered feedthrough assembly previously illustrated in FIG. 37;

FIG. 39 is a cross-sectional drawing of a filtered feedthrough hermeticassembly wherein a single MLCC chip capacitor is used, connected betweenan internal ground pin and an active pin;

FIG. 39A is the electrical schematic of the filter feedthrough assemblyof FIG. 39;

FIG. 40 is very similar to FIG. 39, except that the circuit board hasbeen eliminated and the MLCC capacitor has been directly mounted to theinsulator of the hermetic seal subassembly;

FIG. 41 is very similar to FIG. 2 in that it shows the interior of anactive implantable medical device;

FIG. 42 illustrates a perspective view quadpolar filtered feedthroughsimilar to a prior art design;

FIG. 43 illustrates another perspective view of the structure of FIG.42;

FIG. 44 illustrates the first layer of the multilayer board shown inFIGS. 42 and 43;

FIG. 45 illustrates the second layer of the multilayer board shown inFIGS. 42 and 43;

FIG. 46 illustrates the third layer of the multilayer board shown inFIGS. 42 and 43;

FIG. 47 illustrates a sectional view and includes a circuit board whichis adjacent the hermetic ferrule and hermetic insulator;

FIG. 48 is similar to FIG. 47 but now illustrates two embedded circuittraces;

FIG. 49 illustrates a perspective view of an octapolar filteredfeedthrough utilizing a circuit board with MLCCs;

FIG. 50 is a sectional view taken from section 50-50 from FIG. 49;

FIG. 51 is a top view of a hexapolar filtered feedthrough of the presentinvention;

FIG. 52 is a sectional view taken along lines 52-52 from FIG. 51;

FIG. 53 is a sectional view taken along lines 53-53 from FIG. 51;

FIG. 53A is a sectional view taken along lines 53A-53A from FIG. 52;

FIG. 54 is an enlarged view taken along lines 54-54 from FIG. 52 but isnow showing a new embodiment;

FIG. 55 is very similar to FIG. 8, except that the short lead or pin ofFIG. 8 has been eliminated;

FIG. 56 is very similar to FIG. 55, except that the insulation materialon the wire can be added as separate tubing or even a heat-shrink tubingand in addition the structure of FIG. 56 has no ferrule;

FIG. 57 is very similar to FIG. 54, except the short leadwire pin orstub has been eliminated and the length of the leadwire has beenlengthened to effect a co-braze joint in accordance with the presentinvention in the hermetic insulator, furthermore the ground lead wire iselectrically coupled to the ferrule through a gold braze moat;

FIG. 58 is very similar to FIG. 57 and now FIG. 25 in that, theleft-hand ground pin is grounded through a gold braze joint to embeddedground electrode plates within the hermetic seal insulator;

FIG. 59 is very similar to FIG. 58 and now FIG. 30 in that, the ferrulehas one or more peninsulas which facilitates the grounding of theleft-hand pin;

FIG. 60 is taken from the bottom portion of the exploded view previouslyillustrated in FIG. 9;

FIG. 61 is very similar to FIG. 60, except that it incorporates internalground plates that are contained within the hermetic insulator;

FIG. 62 shows an alternative method of FIG. 61 now using a gold brazemoat;

FIG. 63 illustrates that the right-hand ground pin can also be groundedby a co-machined peninsula of the hermetic seal insulator;

FIG. 64 is very similar to FIG. 8, except that the pin has been formedinto a wire wrapped terminal;

FIG. 65 is very similar to FIG. 64, except that it shows the hermeticterminal subassembly inverted and the feedthrough capacitor has beeneliminated;

FIG. 66A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 66B is the side view of the structure of FIG. 66A;

FIG. 67A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 67B is the side view of the structure of FIG. 67A;

FIG. 68A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 68B is the side view of the structure of FIG. 68A;

FIG. 69A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 69B is the side view of the structure of FIG. 69A;

FIG. 70A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 70B is the side view of the structure of FIG. 70A;

FIG. 71A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 71B is the side view of the structure of FIG. 71A;

FIG. 72A is a perspective view of new embodiment of pin used in thepresent invention;

FIG. 72B is the side view of the structure of FIG. 72A;

FIG. 73 illustrates that the present invention, shown on the left sideembodying body fluid side pin or leadwire and device side were co-joinedor co-brazed, may comprise a hybrid structure wherein, one or more ofthe conductive pathways or conductive vias through the hermetic sealinsulator, has been co-fired forming a conductive via;

FIG. 74 illustrates that a co-fired or co-sintered pin that is co-firedwith via fill material can be combined with the present invention;

FIG. 75 is very similar to FIG. 12, except that an eyelet is used inplace of leadwire and its insulation;

FIG. 76 is taken generally from section 76-76 of FIG. 75 and illustratesthat the capacitor inside diameter or via hole metallization may extendonto the device side of the feedthrough capacitor forming a white-walltire configuration, as previously described in FIG. 12;

FIG. 77 is a sectional view illustrating two and three part pins inaccordance with the present invention now used within a hermeticstructure that is both the insulator and the capacitor; and

FIG. 78 is a chart that details various solder compositions that may beused when manufacturing the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates various types of active implantable and externalmedical devices 100 that are currently in use. FIG. 1 is a wire formeddiagram of a generic human body showing a number of implanted medicaldevices. 100A is a family of external and implantable hearing deviceswhich can include the group of hearing aids, cochlear implants,piezoelectric sound bridge transducers and the like. 100B includes anentire variety of neurostimulators and brain stimulators.Neurostimulators are used to stimulate the Vagus nerve, for example, totreat epilepsy, obesity and depression. Brain stimulators are similar toa pacemaker-like device and include electrodes implanted deep into thebrain for sensing the onset of a seizure and also providing electricalstimulation to brain tissue to prevent the seizure from actuallyhappening. The lead wires that come from a deep brain stimulator areoften placed using real time imaging. Most commonly such lead wires areplaced during real time MRI. 100C shows a cardiac pacemaker, which iswell-known in the art, may have endocardial or epicardial leads. 100Dincludes the family of left ventricular assist devices (LVAD's) andartificial hearts. 100E includes an entire family of drug pumps whichcan be used for dispensing of insulin, chemotherapy drugs, painmedications and the like. Insulin pumps are evolving from passivedevices to ones that have sensors and closed loop systems. That is, realtime monitoring of blood sugar levels will occur. These devices tend tobe more sensitive to EMI than passive pumps that have no sense circuitryor externally implanted lead wires. 100F includes a variety of externalor implantable bone growth stimulators for rapid healing of fractures.100G includes urinary incontinence devices. 100H includes the family ofpain relief spinal cord stimulators and anti-tremor stimulators. 100Halso includes an entire family of other types of neurostimulators usedto block pain. 1001 includes a family of implantable cardioverterdefibrillators (ICD) devices and also includes the family of congestiveheart failure devices (CHF). This is also known in the art as cardioresynchronization therapy devices, otherwise known as CRT devices. 100Jillustrates an externally worn pack. This pack could be an externalinsulin pump, an external drug pump, an external neurostimulator, aHolter monitor with skin electrodes or even a ventricular assist devicepower pack. Referring once again to element 100C, the cardiac pacemakercould also be any type of biologic data recording device. This wouldinclude loop recorders or the like. Referring once again to FIG. 1, 1001is described as an implantable defibrillator. It should be noted thatthese could be defibrillators with either endocardial or epicardialleads. This also includes a new family of subcutaneous defibrillators.In summary, as used herein, the term AIMD includes any device implantedin the human body that has at least one electronic component.

FIG. 2 illustrates a prior art cardiac pacemaker 100C showing a sideview. The pacemaker electronics are housed in a hermetically sealed andconductive electromagnetic shield 102 (typically titanium). There is aheader block assembly 104 generally made of thermal-settingnon-conductive plastic, such as Tecothane®. This header block assembly104 houses one or more connector assemblies generally in accordance withISO Standards IS-1, IS-2, or more modern standards, such as IS4 or DF4.These header block connector port assemblies are shown as 106 and 106′.Implantable leadwires 110, 110′ have proximal plugs 108, 108′ and aredesigned to insert into and mate with these header block connectorcavities 106 and 106′, or, in devices that do not have header blockassemblies built directly into the pulse generator itself.

As used herein, the term “lead” refers to an implantable lead containinga lead body and one or more internal lead conductors. A “lead conductor”refers to the conductor that is inside of an implanted lead body. Theterm “leadwire” or “lead wire” refers to wiring that is either inside ofthe active implantable medical device (AIMD) housing or inside of theAIMD header block assembly or both. Furthermore, as used herein, ingeneral, the terms lead, leadwire and pin are all used interchangeably.Importantly, they are all electrical conductors. This is why, in thebroad sense of the term, lead, leadwire or pin can all be usedinterchangeably since they are all conductors. The term “conductivepathway” can also be used to be synonymous with lead conductor, lead,leadwire or pin o even circuit trace. Additionally, AIMD, as definedherein, includes electronic circuits disposed within the human body thathave a primary or secondary battery, or have an alternative energysource, such as energy induced by motion, thermal or chemical effects orthrough external induction. As used herein, the term “header block” isthe biocompatible material that attaches between the AIMD housing andthe lead. The term “header block connector assembly” refers to theheader block including the connector ports for the leads and the wiringconnecting the lead connector ports to the hermetic terminalsubassemblies which allow electrical connections to hermetically passinside the device housing. It is also understood by those skilled in theart that the present invention can be applicable to active implantablemedical devices that do not have a header block or header blockconnector assemblies such as pulse generators.

FIG. 3A illustrates an isometric cut away view of a unipolar feedthroughcapacitor. Shown, in cut away view, are active electrode plates 134 andground electrode plates 136 both disposed within a capacitor dielectric171. There is a feedthrough hole (passageway) 176, includingmetallization 130. There is also an outside diameter metallization 132.

FIG. 3B shows the unipolar capacitor of FIG. 3A in section, mounted tothe ferrule 122 of a hermetic seal subassembly 116 for an activeimplantable medical device. As shown, the ferrule 122 is configured tobe laser welded 128 into an opening of an AIMD housing previouslyillustrated in FIG. 2 as element 102. The AIMD housing is generally oftitanium or other biocompatible conductive material and forms an overallelectromagnetic shield to help protect AIMD electronics fromelectromagnetic interference emitters, such as cell phones and the like.Accordingly, referring back to FIG. 3B, we see the ground symbol 144representing that EMI signals that may be coupled onto the body side ofthe lead 118, can be decoupled or diverted through the feedthroughcapacitor 124 to the equipotential shield. When high frequencyelectromagnetic signals are diverted from lead 118 to the AIMD housing102, they circulate around the shield and are converted into meaninglessheat (just a few milli or microwatts).

FIG. 3C is the schematic diagram for the feedthrough capacitor of FIGS.3A and 3B. One can see that this is known as a three-terminal device andthat there is significant high frequency attenuation along the length ofthe leadwire between 118 and 118′. Accordingly, the first terminal is onthe body fluid side 118 and the second terminal is on the device side118′, the third terminal being the ground 102,144, where undesirableelectromagnetic interference is diverted to the AIMD housing. It isknown in the art that three-terminal feedthrough capacitors have verylittle to no parasitic series inductance and are therefore, verybroadband low pass filters. This means that low frequency signals, suchas therapeutic pacing pulses or biologic signals pass along from thebody fluid side of the lead conductor 118 to the device side 118′without degradation or attenuation. However, at high frequencies, thecapacitive reactance drops to a very low number and ideally, highfrequency signals are selectively shorted out from the lead conductor118, 118′ to the ferrule 122 and in turn, to the conductive housing 102.

FIG. 3D is an exploded view of the unipolar capacitor of FIG. 3A showingthat it has ceramic cover plates 154, active electrode plates that areinterleaved with ground electrode plates 136 and one or more coversheets disposed on the other end 154. In ceramic engineering, theceramic dielectrics would typically be of BX or X7R having a dielectricconstant of approximately 2000 or higher. It will also be appreciatedthat NP0, which is generally a low k dielectric with a dielectricconstant below 200, could also be used, as taught in U.S. Pat. No.8,855,768, the contents of which are fully incorporated herein byreference.

FIG. 4A illustrates a quadpolar feedthrough capacitor and hermeticterminal subassembly 116 where it has four leadwires 118 a-118 d andfour feedthrough holes (quadpolar). It has a metallic ferrule 122generally of titanium which is ready for laser welding 128 into the AIMDhousing 102 (not shown).

FIG. 4B is a prior art sectional view taken generally from section 4B-4Bfrom FIG. 4A. This illustrates the hermetic terminal subassemblyleadwires 118 a-d passing through the hermetic terminal subassemblyinsulator 120 in non-conductive relationship and also through thefeedthrough capacitor 124 wherein the active electrode plates 134 areelectrically connected 146 to the hermetic terminal subassembly leadwire118 and wherein the feedthrough capacitor ground electrode plates 136are electrically connected 148 to the hermetic terminal subassemblyferrule 122 and gold braze 140. Referring once again to FIGS. 4A and 4B,in each case it is seen that the hermetic terminal subassembly leadwires118 a-d pass all the way through the entire structure, namely, thehermetic terminal subassembly 116 and the feedthrough capacitor 124. Ingeneral, these hermetic terminal subassembly leadwires 118 a-d areelectrically and mechanically continuous (single material) and passthrough from the body fluid side to the inside of the device 100 housing102. Because the hermetic terminal subassembly leadwires 118 a-d passthrough from the body fluid side to the inside of the device housing byway of header block connector assembly 104 or the like, it is veryimportant that these hermetic terminal subassembly leadwire 118materials be both biocompatible, biostable and non-toxic. Generally, inthe prior art, these hermetic terminal subassembly leadwires areconstructed of platinum or platinum-iridium, palladium orpalladium-iridium, niobium or the like. Platinum-iridium is an idealchoice because it is biocompatible, non-toxic and is also mechanicallyvery strong. The iridium is added to enhance material ductility and toenable the hermetic terminal subassembly leadwire to sustain bendingstresses.

FIG. 4C is an electrical schematic representation of the quadpolarfiltered feedthrough assembly 116, 124, as previously illustrated inFIGS. 4A and 4B. Referring once again to FIG. 4C, one can see that theseare feedthrough capacitors and are three-terminal devices. For example,feedthrough capacitor 116, 124 has a first terminal 118 a, a secondactive terminal 118′a and a ground terminal 102, 122. In the art,feedthrough capacitors are known as broadband low pass filters. Theyhave practically zero series inductance and are desirable in that, theywork over a very wide range of frequencies. In general, feedthroughcapacitors and their internal electrode geometries are well known in theprior art. In this case, the feedthrough capacitor is a diverterelement, in that, it diverts RF signals on all four leads to the AIMDhousing as previously described. This is important for the capacitancereactance formula. At very low frequencies, such as biologic sensingfrequencies or biologic therapy frequencies, the capacitor impedance isextremely high and the capacitor acts like it's not present. However, atvery high frequencies, such as frequencies around the area of a cellphone (950 MHz), the capacitor tends to look more like a short circuitand diverts those undesirable signals to the AIMD housing. One isreferred to U.S. Pat. Nos. 4,424,551; 5,333,095; 5,978,204; 6,643,903;6,765,779 all of which are incorporated herein by reference.

FIG. 4D is an exploded view of the quad polar capacitor 132 of FIG. 4A.In the exploded view, you can see that there are four active electrodeplates 134 and one ground plate 136. The effective capacitance areacomes from the overlap of the active electrode 134 with the groundelectrode 136. The greater this overlap area is, the higher thecapacitance of the feedthrough capacitor becomes. One can also say thatit is a multilayer structure. In FIG. 4D, there are two active andground plates shown. This has the effect of increasing the capacitor'seffective capacitance area. It will be appreciated that as many as 400or more ground and active layers could be used.

FIGS. 5, 6 and 7 illustrate an internally grounded prior art feedthroughcapacitor. In general, internally grounded feedthrough capacitors areknown in the prior art with reference to U.S. Pat. Nos. 5,905,627;6,529,103; 6,765,780 and the like, all of which are incorporated hereinby reference. Referring once again to FIG. 5, one can see an internallygrounded feedthrough capacitor, which is octapolar (eight active leads).The eight active leads are labeled 118 a through 118 h on the body fluidside and on the inside of the AIMD housing they are labeled 118′athrough 118′h. The ferrule 122 has a peninsula structure 139, which isconnected to an internal ground pin 118 gnd. Referring now to theoctapolar feedthrough capacitor active electrode plates 134, they aredesigned to overlay in a sandwich fashion the ground electrode plates136. One skilled in the art will realize that one can stack up as manyof these interleaved layers as is required in order to achieve therequired capacitance value and other design factors. The internal groundlead 118 gnd is electrically connected to the ground electrode platelayers 136. The active electrodes 134 a through 134 h are eachelectrically connected through their respective leadwires 118′a through118′h. The overlap between the active electrodes 134 and the groundelectrodes 136 create what is known as effective capacitance area (orECA). The active and ground electrode layers may be interleaved withadditional ceramic layers to build up the dielectric thickness (notshown). In general, the monolithic ceramic feedthrough capacitor 124, asshown in FIG. 6 as element 124, is a result of laminating the variouselectrode layers together and then sintering them at a high temperatureto form a rigid monolithic ceramic block. This is known as a singlefeedthrough capacitor that is multipolar (in this case these areoctapolar or eight active filtered circuits). One can see that there isa perimeter metallization 132 on the outside of the round capacitor fromFIGS. 3A and 4A whereas, in this case in FIG. 6, there is no perimetermetallization 132 at all.

There are several major advantages to internal grounding and removal ofthe perimeter or diameter metallization 132. This is best understood byreferring back to FIGS. 3A through 4B. In contrast to FIG. 3B, withinternal grounding there is no longer a need to apply a diametermetallization 132 as shown in FIGS. 5, 6 and 7. In addition, theelectrical connection 148 has been entirely eliminated between thecapacitor diameter metallization 132 and the gold braze 140 and ferrule122. The elimination of this electrical connection 148 also makes thecapacitor structure 124′ much more resistant to mechanical damage causedby subsequent laser welding 128 of the hermetic seal assembly 116 intothe AIMD housing 102. A significant amount of heat is produced by laserwelding 128 and there is also a mismatch in thermal coefficient ofexpansion materials. By elimination of the electrical connectionmaterial 148, the capacitor 124′ is free to float and is therefore, muchmore resistant to such stresses. Referring once again to FIG. 6, one cansee that the internal ground lead 118′gnd makes a low impedanceconnection from the capacitor's internal electrode plates 136 to theferrule 122. This is what eliminates the need for the electricalconnection material 148, as previously illustrated in FIG. 4. It will beappreciated that only one ground pin is shown in FIG. 6, but somedesigns may require a multiplicity of ground pins spaced apart suchthat, there is a very low impedance connection effectively grounding thecapacitor internal electrodes 136 at multiple points.

Referring once again to FIG. 6, one can see the ceramic capacitorsubassembly 124′ ready to be installed onto the hermetic terminalsubassembly 189. These are shown joined together in FIG. 7 resulting ina hermetically sealed feedthrough capacitor filter assembly 116.

Referring back to FIG. 6, it is important to clarify some confusion asterms of art. The feedthrough capacitor 124′ can also be described as athree-terminal feedthrough capacitor with multiple via holes orfeedthrough holes. In a confusing manner, the hermetic terminalsubassembly 189 is often referred to in the art as a hermeticfeedthrough. Therefore, we have the term feedthrough applying both tothe feedthrough capacitor and to the hermetic terminal assembly. As usedherein, these are two separate and distinct subassemblies, which arejoined together in FIG. 7 to become a feedthrough filter hermeticterminal assembly 116 ready for installation into an opening of an AIMDhousing. Referring once again to FIGS. 5 and 6, one will appreciate thatleadwires or lead conductors 118′, 118 are continuous leadwire. In otherwords, on the body fluid side, the leadwire is of the same material ason the device side. This is typical in the prior art. Referring onceagain to FIG. 6, one can see that the internal ground lead 118′gnd doesnot extend through to the body fluid side of the hermetic terminalfeedthrough subassembly 189. It will be appreciated that it could beeasily and readily extended to the body fluid side, but in mostembodiments, it is not necessary.

An issue with the use of platinum for hermetic terminal subassemblyleadwires 118 a-d is that platinum has become extremely expensive andmay be subject to premature fracture under rigorous processing such asultrasonic cleaning or application use/misuse, possibly unintentionaldamaging forces resulting from Twiddler's Syndrome. Accordingly, what isneeded is a filtered structure like a feedthrough capacitor assembly 116which eliminates these high-priced, platinum, platinum-iridium orequivalent noble metal hermetic terminal subassembly leadwires 118. Foradditional examples of hermetic terminal subassemblies with feedthroughcapacitors that employ leadwires 118, one is referred to U.S. Pat. Nos.5,333,095, 5,896,267, 5,751,539, 5,905,627, 5,959,829, 5,973,906,6,008,980, 6,159,560, 6,275,379, 6,456,481, 6,529,103, 6,566,978,6,567,259, 6,643,903, 6,765,779, 6,765,780, 6,888,715, 6,985,347,6,987,660, 6,999,818, 7,012,192, 7,035,076, 7,038,900, 7,113,387,7,136,273, 7,199,995. 7,310,216, 7,327,553, 7,489,495, 7,535,693,7,551,963, 7,623,335, 7,797,048, 7,957,806, 8,095,224, 8,179,658 thecontents of all of which are incorporated herein by reference.

FIG. 7A is the electrical schematic for the feedthrough filteredhermetic terminal 116 previously described in FIGS. 5, 6 and 7.Referring once again to FIG. 7A, one can see the telemetry pin T, whichpasses through the filtered hermetic terminal assembly 116 without anyappreciable capacitance to ground. In other words, it would beundesirable to have any high frequency filtering of the telemetryterminal since this would preclude the ability to recover storedinformation or program the AIMD device remotely. Leadwires 118 a through118 h all have feedthrough capacitor hermetic terminal assemblies 116,124 as shown. The internal ground pin 118 gnd is shown only on thedevice side of the hermetic terminal subassembly 189. Referring onceagain to FIGS. 5, 6, 7 and 7A, it will be noted that the feedthroughfilter hermetic seal subassembly has been inverted with reference toFIGS. 2, 3 and 4. It should also be noted that the capacitor 124 isstill on the device side; it's just drawn inverted.

FIG. 8 illustrates the present invention where leadwires 118 on the bodyfluid side could be directed to a connector block cavity 104, 106 ordirectly to lead conductors (see FIG. 2). In general, body fluid sideleadwires 118 must be of biocompatible, non-toxic and biostablematerials. This limits the materials to platinum, palladium, niobium,tantalum, titanium and equivalents or combinations thereof. Leadwires118 are co-brazed 138, co-welded 424 or both to short platinum(palladium or the like) pins (leadwires) 117, as illustrated. When thegold braze 138 flows, it forms a strong mechanical and hermetic sealboth to the high cost leadwire 118, to the short platinum pin 117 and tothe sputtering 150, 152 of the insulator 188. Referring to the left-handhermetic braze 138, one can see that it is disposed towards the deviceside of the hermetic seal insulator 188. On the right side, the goldbraze 138′ extends all the way to the right side of the body fluid side.In another embodiment, not shown, it will be appreciated that theleft-hand side of hermetic seal 138 could be moved and disposed on thebody fluid side. In this case, the platinum or equivalent solderable pin117 would have to be extended in length. Most AIMD manufacturers avoidusing pure platinum or palladium leadwires because it has been shownthat after repeated bending, they fracture. Accordingly, iridium istypically added to long leadwires in AIMDs because a low percentage ofiridium makes the leadwire much more resistant to bending fractures.However, as illustrated in FIG. 8, these short leadwire segments 117will never be exposed to bending forces, therefore, pure platinum can beused. Using pure platinum for this segment of leadwires is an enormousadvantage because pure platinum is very noble and does not form surfaceoxides readily. The problem with platinum-iridium leads orpalladium-iridium leads is the iridium, at the surface, tends to oxidizemaking properly wetting these leads with solder (or a thermal-settingconductive adhesive) a problem. Referring back to FIG. 8, it isdesirable that the short pin 117 not only be very noble (in other words,not oxidize), but also have a very high melting point. This is so itwill maintain its structural integrity while the gold braze preform 138is reflowed in a gold brazing furnace operation. The melting point ofpure gold is 1064° C. The melting point of platinum is 1768° C. Themelting point of palladium is 1555° C.

Referring once again to FIG. 8, one can see that there is an adhesionlayer 152 and a wetting layer 150 that have been applied to the insidediameter and outside diameter (or perimeter) of the alumina ceramicinsulator 188. These are required because gold preforms generally willnot wet or adhere to bare alumina insulators. The alumina insulatorshown in FIG. 8 has been manufactured in a separate manufacturingoperation and sintered and fired (as hard as a rock). Through sputteringprocesses, an adhesion layer 152 is first laid down and then over that,a wetting layer 150 is laid down. This can also be done by somemanufacturers in a single process, which combines wetting and adhesionproperties into one (such as niobium). Other processes use a molybdenumadhesion layer and then a sputtered titanium layer to which gold brazewill readily wet to. In summary, in order for the gold braze preforms138 and 140 to properly flow and wet to the insulator 188, there mustfirst be layers sputtered onto the ceramic insulator, which will performboth adhesion and wetting characteristics. This will not be furtherdescribed throughout this invention, but it will be appreciated thatevery time a gold braze is shown, that the adhesion/wetting layer ispresent. It will also be noted that on the outside diameter (whennecessary) and inside diameter holes of the feedthrough capacitor 124,that there is a metallization 130. This can be a multilayer process,such as a copper and tin or copper and silver during an electroplating.The embodiment shown throughout this invention would be one of applyinga silver or palladium-silver bearing glass frit, which is fired on as asingle layer 130. It will be appreciated that the metallization 130 orcapacitor 124 outside diameter or perimeter metallization 132 be shownthroughout this invention as a single layer (but as previouslymentioned, it could consist of several different layers). It will alsobe appreciated that ceramic feedthrough capacitor metallizations 130,132 can be a metal bearing glass frit or be plated on when the platingoperation may consist of selectively plating on one or more under-layersand then a final layer, which would be solderable or receptive through athermal-setting conductive adhesive 148.

It will be appreciated that the machined ferrule 122, illustrated inFIG. 8, could also be replaced by a stamped ferrule or even a two-pieceferrule, as taught in U.S. Pat. Nos. 8,927,862; 9,431,814; and8,604,341; and U.S. Patent Publications 2015/0245468 and 2016/0287883,the contents of all of which are incorporated herein by reference.Referring once again to FIG. 8, the machined ferrule 122 is relativelyexpensive, not just because of the machining process, but because themachining starts with a solid block of titanium and there is a greatdeal of scrap produced. A stamped metal ferrule or a two-piece stampedferrule thereby, significantly reduces the machining costs and alsoresults in a material savings, as shown later in FIG. 22. It will beunderstood that any of the machined ferrule in this teaching could bereplaced with stamped ferrules in accordance with the referenced patentsand publications.

Referring once again to FIG. 8, it will be appreciated that the deviceside leadwire 118′ can now be of very low cost materials, includingcopper, tin, or the like. This leadwire 118′ could be a solid wire, canbe a stranded wire, can be a braided wire and the like. It will beappreciated that, in the prior art, a high cost platinum-iridium orpalladium wire would be in a single piece all the way to the device sideto the body fluid side. These one piece leadwires were previouslydescribed as 118, 118′ in FIG. 3B, also in FIGS. 4A and 4B, and FIGS. 5,6 and 7. The novel two part co-welded or co-brazed leadwires of thepresent invention, allow one to then use very low cost leadwires 118′ onthe inside of the device or the device side, which route a filterfeedthrough assembly 116 to device electronics circuits, including acircuit board 126, as previously illustrated in FIG. 2. The advantage ofstranded wires or braided wires is they are generally more resistant toshock and vibration load. Stranded or braided wires are also moreflexible and more easily routed to internal circuit boards (not shown).Referring once again to FIG. 8, it will be appreciated that the shortpins 117 could also comprise nickel, in that, nickel has a very highmelting point and could accept gold braze 138.

In general, two-part pins as described in FIG. 8 have never beendescribed in any prior art that the inventors are aware of. The closestprior art is U.S. Pat. No. 5,867,361 to Wolf, et al., herein referred toas the Wolf patent. Wolf FIG. 1, on the bottom, shows a leadwire/leadconductor 30, which would be routed to an implantable lead conductive indistal electrodes (not shown). This lead is co-brazed 65 to a hermeticseal insulator 90 as shown. There is a feedthrough capacitor 50illustrated and a nail head structure 60 that also forms a wire bondpad. There is an electrical conductive material 75, which couldcomprise, for example, a solder or a thermal-setting conductive adhesivethat connects between the nail head pin structure 60 and the gold braze65, which is also gold brazed to the body fluid side pin 30. To highreliability engineers, such as in the military and space business, thisputs a series type electrical connection 75 in the system. Such a seriesconnection can readily compromise the reliability of the overall systemif there is shrinkage of the electrical conductive material 65,vibration fractures, micro-cracks or separation of these serieselements. The present invention is very different from the Wolf patent,in that, the body fluid side lead 118 is co-welded or co-joined to thedevice side pin 117. As described in FIG. 8, the body fluid sideleadwire 118 and the device side pin 118 are co-joined by extremelyreliable welding or brazing processes. These form a very strongmetallurgically reliable bond as well as a very low resistance lowimpedance electrical connection. In summary, the present inventionovercomes the difficulties as described in the Wolf patent.

Accordingly, it is the electrical connection material 148 that connectsbetween the capacitor outside diameter metallization 132 to the goldbraze 140 that makes the low impedance (very low resistance) RFdiverting circuit to the ferrule 122. One can also see that there is anon-conductive polymer, such as an epoxy or a polyimide covering 147disposed over the feedthrough capacitor. This material 147 helps inbinding to the low cost leadwires 118 and improves their pull strength.In addition, the non-conductive epoxy or fill 147 provides a pleasingcosmetic appearance.

FIG. 8A is very similar to FIG. 8, except that in this case, theinsulator 188 sits on top of the ferrule structure 122. The gold braze140 has been wetted between the alumina insulator 188 and the ferrule.As previously taught, there is an electrical connection material 148that connects the feedthrough capacitor outside diameter or perimetermetallization 132 to the gold braze 140, which in turns makes anon-oxidized electrical connection to the ferrule 122. As previouslytaught, a direct connection to titanium is generally undesirable due tothe build-up of titanium oxides, which can be resistive or evensemi-conductive.

FIG. 8B is very similar to FIG. 8, except that in this case, there is nogold braze between the insulator 188 and the ferrule 122. In this case,there is a CERMET material 131, which is co-sintered into the ferrule122 and forms a strong mechanical and hermetic seal between insulator188 and ferrule 122. A CERMET in the art, is known as ceramic metalpaste, which is then sintered at high temperature and is, aftersintering, highly conductive. Accordingly, as one can see, the capacitorelectrical connection material 148 connects between the capacitoroutside diameter or perimeter metallization 132 to at least part of theCERMET 131 so that we do not have a problem with direct contact, only tothe titanium ferrule surface 122. Conductive via fill materials ofalumina/platinum or pure platinum are described, but other materialsincluding Cermets may be used. For example, it will be known to thoseskilled in the art from this teaching that other nonlimiting ceramics,glass ceramics, and/or glass oxides may be added to the metal-containinginks/pastes to customize TCE matching/transition pending core materialand/or insulator material selections. Palladium may be used instead ofplatinum. Other nonlimiting biocompatible metals and alloys that may beused in place of platinum include niobium, platinum/palladium, stainlesssteels, and titanium. Furthermore any of the following list of materialsmay be used alone or combination with any of the materials alreadydiscussed or within this list: Gold (Au), silver (Ag), iridium (Ir),rhenium (Re), rhodium (Rh), titanium (Ti), tantalum (Ta), tungsten (W),zirconium (Zr), and vanadium (V), Cobalt Chromium Molybdenum Alloy,Cobalt Chromium Nickel Iron Molybdenum Manganese Alloy, Cobalt ChromiumTungsten Nickel Iron Manganese Foil, Cobalt Nickel Chromium IronMolybdenum Titanium Alloy, Cobalt Nickel Chromium Iron MolybdenumTungsten Titanium Alloy, Cobalt Nickel Chromium Molybdenum Alloy, CopperAluminum Nickel Alloy, Copper Zinc Alloy, Copper Zinc Aluminum NickelAlloy, Copper Zinc Silver Alloy, Gold Platinum Palladium Silver IndiumAlloy, Iron Chromium Alloy, Iron Chromium Nickel Alloy, Iron ChromiumNickel Aluminum Alloy, Iron Chromium Nickel Copper Alloy, Iron ChromiumNickel Copper Molybdenum Niobium Alloy, Iron Chromium Nickel CopperNiobium Alloy, Iron Chromium Nickel Copper Titanium Niobium Alloy, IronChromium Nickel Manganese Molybdenum Alloy, Iron Chromium NickelMolybdenum Alloy, Iron Chromium Nickel Molybdenum Aluminum Alloy, IronChromium Nickel Titanium Molybdenum Alloy, Iron Manganese ChromiumMolybdenum Nitrogen Alloy, Nickel Platinum Alloy, Nitinol, NickelTitanium Alloy, Nickel Titanium Aluminum Alloy, Niobium-Titanium Alloy,Platinum Iridium Alloy, Platinum Palladium Gold Alloy, Titanium AluminumVanadium Alloy, Titanium Based Aluminum Iron Alloy, Titanium BasedAluminum Molybdenum Zirconium Alloy, Titanium Based Molybdenum NiobiumAlloy, Titanium Based Molybdenum Zirconium Iron Alloy, Titanium basedNiobium Zirconium Alloy, Titanium based Niobium Zirconium TantalumAlloy, Titanium Molybdenum Alloy, Titanium Niobium Alloy, TitaniumPlatinum Alloy, Titanium-based Molybdenum Zirconium Tin Alloy.

Examples of some PAC, Cermet, CRMC ceramic/metal pairings include, butare not limited to:1. Alumina (Al2O3) or zirconia (ZrO2) including various stabilized orpartially stabilized zirconia like zirconia toughened alumina (ZTA) andalumina toughened zirconia (ATZ) with platinum (Pt) or palladium (Pd)2. Alumina (Al2O3) or zirconia (ZrO2) with iridium, rhenium, rhodium,various Pt alloys (e.g., Pt—Ir, Pt—Pd, Pt—Rh, Pt—Re, Pt—Au, Pt—Ag etc.),Pd alloys (e.g., Pd—Ir, Pd—Re, Pd—Rh, Pd—Ag, Pd—Au, Pd—Pt, Pd—Nb, etc.),Au alloys (e.g., Au—Nb, Au—Ti, etc.), Au alloys (e.g., Au—Nb, Au—Ti,etc.), and Ti alloys (e.g., Ti—Al—V, Ti—Pt, Ti—Nb, etc.)Any combination of the ceramics and metals is theoretically suitable fora Cermet used as disclosed herein.It will also be obvious to one skilled in the art that more than onemetal/ceramic, metal/glass oxide, or metal/ceramic/glass oxideformulation may be used to surround the core conductive material ofink/paste, wire, or combinations of both, to create a layering effectabout the core material(s) along the longitudinal axis of the via toachieve optimal transition for CTE matching at the respective matingmaterial interface(s).

FIG. 8C is very similar to FIGS. 8, 8A and 8B, except in this case, theferrule 122 is round. It has a notch 121 for capturing the AIMD housing102 where a convenient laser weld 128 may be formed. When using the word“round” we are referring to the cross-sectional area of the ferrule,which, of course, can be of many other shapes, including oval,elliptical and the like. The cross-section shown in FIG. 8C could beround, as previously illustrated in FIGS. 3A and 4A; however, it willalso be appreciated that the ferrule of FIG. 8C could also be of more ofa rectangular shape, as previously illustrated in FIGS. 5, 6 and 7.Referring once again to FIG. 8C, this shows a round cross-section of theferrule and if the feedthrough capacitor is also round, then generallythe ferrule 122 would form a toroidal or donut shape.

FIG. 8D is very similar to FIG. 8 through 8C, except that in this case,the alumina ceramic 188 has been replaced with a glass seal 191. Thismay be a compression glass or a fusion glass, which are well known inthe art. In this case, the novel two-part pin of the present inventionhas been pre-welded 424 (it will also be appreciated that the leadscould be pre-co-brazed 138′ together before the glass sealing operationinstead of welded) so it can be placed into the glass sealing fixture asthe glass wets to both the leads and the inside of the ferrule at onceforming a mechanical and hermetic seal. An optional alumina ceramic orequivalent insulator sheet 193 is shown. This insulator 193 would beplaced on top of the glass pre-form prior to the glass sealing process.When the glass 191 becomes molten, the advantage of having an alumina orequivalent ceramic sheet 193 disposed towards the body fluid side, isthat very little of the glass 191 ends up being exposed to body fluids,which can act as solvents. In other words, the alumina sheet 193 makesthe assembly of FIG. 8D more stable over the long life of an activeimplantable medical device.

Referring once again to FIG. 8D, since there are no gold brazes, thereare no required metallization layers 150,152.

FIG. 8E is similar to FIG. 8, except that in this case, the diameter orperimeter of a feedthrough capacitor 124 is enlarged. This is oftenrequired for high voltage implantable cardiofibrillator devices wherethe dielectric thickness has to be quite high so the capacitor has ahigh voltage rating. Accordingly, in order to increase the feedthroughcapacitor's effective capacitance area (ECA), it is required to make thecapacitor larger in either its length, width or outside diameter. Thiscreates a problem, in that, the capacitor outside diameter metallization132 no longer aligns with gold braze 140. In this case, a small orseparate round or square or other shape gold pad has been co-brazed,which is not part of the hermetic seal 140. This small area of goldbraze 141 allows for the capacitor metallization 132 to be electricallyconnected 148 to a non-oxidized surface and therefore, provide a verylow resistivity path to the ferrule 122 to the AIMD electromagneticshield housing 102.

FIG. 8F is similar to FIG. 8, except that the ferrule structure 122 hasbeen modified such that the capacitor 124 fits partially down into theferrule. Electrical attachment material 148 comprises a thermal-settingconductive adhesive, such as a conductive epoxy or a conductivepolyimide or a solder or the like. It makes an electrical connectionbetween the capacitor metallization 132 and gold braze 140 asillustrated. Having the capacitor sit down part way into the ferruleallows automatic assembly by dispensing of thermal-setting conductiveepoxy or solders by robots. One is referred to U.S. Pat. No. 6,643,903,the contents of which are fully incorporated herein by reference.

Referring now to FIG. 9, after the hermetic seal subassembly 189 isformed from FIG. 8, the capacitor 124 is subsequently added. First, theinsulator assembly 189 is inverted and an optional adhesive insulativewasher 206 is placed against it as shown. The capacitor 124 is disposedon top of the adhesive washer, which is then cured in an elevatedtemperature. This not only firmly and mechanically attaches thefeedthrough capacitor 124 to the hermetic seal subassembly 189, but italso confines the area around the platinum, palladium or alloys thereofpins 117, such that a subsequent soldering operation 410 cannot flowbetween the capacitor and the insulator, thereby, shorting out from leadto lead or lead to ferrule (ground). Referring back to FIG. 9, it willalso be appreciated that the electrical connection material 410 couldalso comprise a thermal-setting conductive adhesive, such as aconductive polyimide or conductive epoxy. It's extremely important inthe case of use of thermal-setting conductive adhesives, that aninsulating washer 206 be used, such that the conductive material, suchas silver particles, in the thermal-setting conductive adhesives, do notmigrate or short out from pin to pin or from pin to ferrule or from pinto ferrule gold braze 140. A low cost insulated (insulation 123 isoptional) lead 118′ is placed along with a solder preform 410. This isbest illustrated in FIG. 9 where the hermetic seal subassembly 189 hasbeen inverted and one can see the two platinum, palladium or alloysthereof pins 117 sticking up. The insulative washer 206 is then disposedover the pins 117 and the feedthrough capacitor 124 is placed adjacentthe insulating adhesive washer 206. This is then pre-cured so they arefirmly adhered and mechanically bonded together. During the curing ofadhesive washer 206, it is usually required that a weighting or a springfixture (not shown) be placed on the top (device side) of thefeedthrough capacitor 124. This pushes the feedthrough capacitor firmlyagainst the adhesive washer 206 and the surface of the insulator 188 sothat they all bond together. Then, a solder preform 410 is placed into acounter-bore or counter-sink 127 in the device side surface of thefeedthrough capacitor. Next, a low cost leadwire, which is typically atinned-copper leadwire 118′, is placed through the solder preform 410.The length of the conductive part of this leadwire 118′ is chosen sothat the low cost tin-copper leadwire will either touch or become veryclose to the platinum, palladium or alloys thereof pins 117 of thehermetic insulator.

FIG. 10 illustrates the completed assembly prior to reflowing the solderpreform 410.

Referring now back to FIG. 8, one can see that the assembly 116 has beeninverted in comparison to FIG. 10, but the solder preform 410 hasreflowed and is fully flowed around the tin-copper portion 118′ of thelow cost device side leadwire and also around the short platinum,palladium or alloys thereof pins 117 from the hermetic seal subassembly189. FIG. 8 increases the reliability of the wiring to the device sideof the electronics through lead 118′ with its optional insulation 123.As one can see, the reflow solder connection 410 not only forms a buttjoint between the low cost leadwire 118′ and pin 117, but also thesolder 410 flows all about both leads 118′ and 117, thereby making theelectrical connection not only a butt connection, but also a shearconnection. It will be known to reliability engineers that solder jointsthat embody shear stresses will be more resistant to shock vibration,reflow and the like. Shear forces are also set up between the solder 410and the inside diameter of the capacitor feedthrough hole metallization130. This double shear increases the mechanical strength of theattachment of the low cost leadwire 118′ and also increases its pullstrength force. It will also be appreciated that instead of a solderpreform 410, one could use a thermal-setting conductive adhesive, suchas a conductive epoxy or a conductive polyimide.

Referring back to FIG. 8, one can see that the solder (or equivalentmaterial) 410 has flowed all about the exposed end portion of theplatinum/palladium pin 117 and the low cost leadwire (tin/copper) 118′.As one can see, there is both a butt joint and a sheer joint formed bysolder flowing all around the outside diameters of both pin 117 andleadwire 118′. The choice of solders for making connection 410 aresomewhat limited in that, they need to have a relatively high meltingtemperature. This is because of the subsequent laser welding operation128 wherein, the ferrule 122 is joined mechanically and hermetically tothe AIMD housing 102. The laser welding operation 128 elevates theentire structure to a fairly high temperature (approximately 260° C.).This rules out the use of low temperature solders 410, which would havemelting points below 260° C. There is another property of the overallassembly 116 that is imposed by the medical implant industry. Thisproperty is known as leadwire pull strength. During qualification,customers require leadwire pull strengths ranging anywhere from two tofour, or even five pounds in range. This generally is done in a pullstrength tester where the leads are put in tension. The inventors testedthe assembly of FIG. 8 with two different high temperature solders 410.One, embodying SN10 and the other was using AG1.5. Both of these soldershave reflow temperatures in the range of 290° C. The inventors performedvarious pull strengths and found that the pull strengths always exceededtwo pounds and in many cases, depending on process control, exceededseven pounds. Worse case experiments were run with the pins 117 andleadwires 118′ not inside of a feedthrough capacitor. In other words,the two ends were joined just with solder and a certain amount of solderspread over the side walls. It was encouraging to note that in no casedid the pull strength of these worse case assemblies, fall below twopounds. Subsequent testing in the inside diameter feedthrough capacitorsgenerally showed pull strengths in the range of six to seven pounds.Accordingly, the inventors are satisfied that the novel arrangement asshown in FIG. 8, will meet both the high temperature, pull strength, theshock and vibration, and the high temperature resistance requirements ofthe active implantable medical implant industry. Generally, the pulltesting conducted by the experimenters placed a tensile load onleadwires 118′ until the point of failure.

It is also desired that the solders contain less than 20-25% Sn as theinventors have found that solders with a higher Sn content becomebrittle and can induce cracks in the ceramic capacitor body whenthermally shocked. Such cracks can result in latent electrical fieldfailures. Two example solders would be AG1.5 or SN10. AG1.5 is 97.5% Pb,1% Sn, and 1.5% Ag with the balance being lead and it has a very highmelting point, close to 300° C. SN10 is a composition comprising tin andlead and also has a very high melting point. SN10 is 88% Pb, 10% Sn and2% Ag. Solders that contain silver are desirable to prevent leaching ofthe terminations from the ceramic capacitor. The chart shown as FIG. 78details various solder compositions that may be used by one skilled inthe art when manufacturing the present invention. This list is not meantto be a full and complete list, but rather shows some of the soldercompositions that could be used.

Referring once again to FIG. 8, one can see that the body fluid side,low cost leadwire 118 can have a gap between it and the short platinum,palladium or alloys thereof pin 117. This gap is shown on the left-handside of FIG. 8. Referring again to FIG. 8, on the right-hand side, onecan see that the body side leadwire 118 has been pre-welded 424 to thepin 117. This pre-welding 424 guarantees that the mechanical andelectrical connection be very robust, but it also facilitatesmanufacturing and assembly just prior to the gold brazing operation 138.It is much easier for an operator to drop in a single lead into a carbonboat before it goes into the gold brazing furnace, then two pieces shownas the left-hand side 117, 118 of this figure. It will also beappreciated that between the device side leadwire 118′, there may be asmall gap with the short pin 117, as shown on the left, or the two maybe butted directly against each other, as shown on the right. It shouldalso be noted that the melted solder preform 410 picks up additionalstrength, not only because it is in sheer around the circumference ofpin 117 and leadwire 118′, but it is also wetted to the insidefeedthrough capacitor diameter metallization 130. Accordingly, thesolder preform 410 not only mates around pin 117 and 118′, but it alsowets completely to the ceramic capacitor 124 inside diameter offeedthrough hole metallization 130. This creates additional sheerstrength. This goes to facilitate the requirement in the industry thatthe device side leadwire have a very high pull strength. In general,pull strengths are specified generally between the range of 2 lbs. to 5lbs. This is equally applicable to the body fluid side leads 118 and thedevice side leadwires 118′. Accordingly, it is very important thatprocess controls ensure that the solder preform 410 flows very evenlyaround both pins 117 and leadwire 118′ and also properly wets themetallization 130 (without having it dissolve into the solder, asituation known in the industry as leaching). Ideally, it wouldpreferable to be able to flow the solder preform 410 without the use offluxes. If one uses a flux, then one must perform cleaning steps toremove the flux. Accordingly, the assembly as illustrated in FIG. 8, isbest accomplished either in a conveyor-type curtain soldering furnace oras a bulk process in a device called a DAP sealer. In both cases, thesoldering can be accomplished by either reducing or inert gases, therebyeliminating the need for fluxes and also a temperature profile could becreated where the relatively fragile ceramic capacitor 124 can be slowlyheated up and the solder 410 molten stage can be held to a relativelyshort amount of time and then the entire assembly is then slowly cooleddown. It is desirable not to have the high temperature solder 410 bemolten for too long as the capacitor termination material 130 canactually dissolve or leach undesirably into solder 410.

Referring once again to FIG. 8, one can see that on the device side, theceramic capacitor has counter-sinks 127 to facilitate placement of thesolder preform 410. This counter-sink is best viewed in FIG. 9, aselement 127. It will also be appreciated that the counter-sink could bereplaced by a counter-bore or even a straight through hole as will befurther described. Referring once again to FIG. 8, one can see thatthere are counter-bores 129 placed in the insulator 188 of the hermeticterminal subassembly 189. These allow for convenient placement of goldbraze preforms (not shown).

Referring back to FIG. 8D, it is very similar to FIG. 8, except that thehermetic seal 191 is now a glass-fused or compression glass seal.Referring once again to FIG. 8, the hermetic seal 188 is typically ofalumina, which is gold brazed to the ferrule 122; thereby, forming ahermetic seal 140. There are also gold brazes 138 and 138′, aspreviously described in FIG. 8, which also form a hermetic seal betweenthe alumina or ceramic insulator 188 and both body fluid side leads 118and device side leads, short lead pins 117. FIG. 8D is a similarstructure, except the hermetic seal to the ferrule 122 is accomplishedby the sealing glass 191. There is also a hermetic seal formed to thetwo-part leads 118 and 117, again, either by a fusion or a compressionsealing of the glass. In FIG. 8D, it is not possible to have the bodyfluid side lead 118 have a gap between it and the short lead pin 117.Accordingly, as previously described in FIG. 8, there is a welding orjoining operation 424, which is first performed before the glass sealcan be accomplished. It will be understood by those skilled in the art,that any of the embodiments shown throughout this invention that show abrazed ceramic type seal, could be replaced by the glass seal, as shownin FIG. 8D. Referring once again to FIG. 8B, it will be appreciated thatthe insulating washer 206 could be replaced by a thin ceramic, such asan alumina washer. There could also be an alumina washer 193 disposed ontop of the glass seal 191. The reason for the alumina washer 193 isthat, the glass seal would bond very tightly to it; thereby, adding tothe overall strength and hermeticity of the package. It will also beappreciated that instead of a fusion or a compression glass 191, therecould also be a number of ceramic glasses that could be used. Referringonce again to FIG. 8D, one will see that there is a gold braze area 141that can be continuous or discontinuous or only in spots on top or onthe device side of the ferrule 122. This provides an oxide-freeelectrical connection surface to which electrical connection material148 forms a low impedance connection between the ferrule and the outsidediameter or perimeter metallization 132 of the feedthrough capacitor124. Problems associated with this are described by U.S. Pat. Nos.6,765,779; 9,108,066; 9,427,596 (oxide-free metal addition), thecontents of all of which are incorporated herein by reference. In apreferred embodiment, the oxide-free material 141 would be a gold braze.However, the reference patents also show that a number of other oxideresistant materials could be used to perfect a low impedance electricalconnection between the capacitor outside diameter perimetermetallization 132 and ferrule 122.

Now referring to FIG. 9, by focusing only on the bottom portion 189,which is the hermetic terminal subassembly, one can see that when thegold braze 138 is placed through gravitational and capillary action inthe gold braze furnace, it will flow down and form the gold brazehermetic seal joint 138. It is important that this hermetic seal joint138 encapsulate both the short pin 117 and the body fluid side leadwire118. Referring now to FIG. 8, the hermetic seal subassembly 189 has beeninverted. Since the gold braze joints 138 and 140 have been formed atvery high temperature, they will not be disturbed nor will they reflowduring the subsequent capacitor 124 soldering operation 410. It isimportant to realize that in a typical manufacturing operation, thehermetic terminal subassembly 189 is manufactured in an entirelydifferent manufacturing line with a different set of controls, includingbraze furnaces and the like. It is equally important to note that thefeedthrough capacitor assembly 124 is generally performed in an entirelydifferent manufacturing line (usually in Class 10,000 or better cleanrooms). It is a monolithic device consisting of alternating layers ofground and active electrodes, which goes through a number of binderbake-out and then sintering operations. Subsequent to that,metallization layers 130 and outside diameter metallization layer 132are applied, either by electroplating, by applying conductive glassfrits (and firing) and the like. In the final operation shown in FIG. 9,the capacitor subassembly 124 is adhered 206 to the hermetic terminalsubassembly 189 and at the same time, device-side leadwires 118′ areco-joined.

Referring once again to FIG. 9, one can see that after the solderpreform 410 is reflowed, one still needs to make the electricalconnection from the capacitor outside diameter perimeter metallization132 to the gold braze 140 of the ferrule 122 using electrical attachmentmaterial 148 as shown in FIG. 8. This attachment 148 could be performedprior to the solder reflow 410 or after. In one embodiment, theelectrical attachment material would be a thermally-conductivepolyimide, which is cured around 290 to 300° C., but can withstandshort-term temperatures up to 500° C. So in this case, the capacitordiameter or perimeter electrical connection 148 would first be formedand then the solder preform 410 would subsequently be reflowed at around300° C.

Referring once again to FIG. 9, at the bottom is the hermetic sealsubassembly 189. This also appears inverted in FIG. 8 with the capacitor124 attached to it. The short pins 117 could, of course, be of platinumor palladium as described, but also could be of a variety of othermaterials. It should be noted that these short pins 117 are neverexposed directly to body fluid and therefore, they do not need to bebiocompatible or non-toxic. For example, pins 117 could be of nickel. Ifthe pins were of nickel, they could still be co-gold brazed 138 to thebody fluid side leadwires 118. In order to facilitate ready soldering tothe capacitor inside diameter metallization 130 and the low costleadwire 118′, it would be preferred if nickel leadwires or the likewere either tinned, solder, flowed or electro-plated etched and thentin-dipped or electroplated, for example, with gold or a gold flash tofacilitate solderability. This could easily be achieved in a subsequentoperation after building the hermetic seal subassembly as illustrated as189. Another option would be to sputter a layer of gold, for example, orplatinum onto the exposed ends of the pins 117 to facilitatesolderability.

It is noted that the body fluid side leadwires 118′ have a first end 341that will at least be partially disposed within the passageway of thefeedthrough filter capacitor while the second end 342 will be disposedpast the feedthrough filter capacitor configured to be connectable toelectronics internal to the AIMD.

FIG. 10 illustrates the capacitor 124 co-joined to the hermetic sealsubassembly 189 by adhesive washer 206. The device side leads 118′ havebeen placed through their solder preforms 410. FIG. 10 illustrates theentire assembly 116 just prior to reflow of the solder preform 410.After the solder preform 410 is reflowed at an elevated temperature, itwill result in the structure 189, as illustrated in FIG. 8 (inverted).As can be seen, the solder preform 410 flows all around the two pins117, 118′.

FIG. 11 is very similar to FIG. 8 except on the capacitor device side,counter-bores 135 are shown instead of counter-sinks 127. The right sideof the device now has a wire bond pad 131 which may be proud of thefeedthrough capacitor 124. This nail head 131 may be proud of the deviceside surface of the feedthrough capacitor 124 (as shown) or it may beflush with the surface (not shown), or it may be reduced below thesurface (not shown).

FIG. 12 is very similar to FIG. 8, except that the counter-sinks 127have been eliminated on both the right and the left side of the deviceside of the feedthrough capacitor 124. This will make it more difficultto place a solder preform 410 and have it reflow properly. However, itwill be understood by one skilled in the art that counter-bores,counter-sinks or combination and variations thereof can be used, oralternatively, as shown in FIG. 12 no such structures are used to helplocate and place the solder preform 410.

Referring back to FIG. 12, one can see that the feedthrough capacitorinside diameter (or via hole) metallization 130 has been extended 411onto the device side of the feedthrough capacitor 124 such that it formsa circular portion, which is also known in the industry as a white-walltire shape. As previously described, this metallization 130, 411 can bemechanically and electrically adhered to the capacitor electrode platesby firing a silver or palladium-silver glass frit, electroplating or thelike. In all cases, the metallization 130, 411 firmly adheres to thebody of the feedthrough capacitor 124. The presence of the white-walltire metallization 411 allows for the solder 410 to form a fillet 410′between the lead conductor 118′ and metallization band 411. This forms asolid fillet, which is known in the industry to have very high pull andbending strength. In other words, the white-wall tire metallization 411and corresponding solder (or thermal-setting conductive adhesive) fillet410′ adds greatly to the pull strength of the lead 118′, 123.

FIG. 13 is very similar to FIG. 8, except that in this case, thecounter-bores on the device side of the hermetic insulator 188 have beenreplaced by counter-sinks 133.

FIG. 14 is very similar to FIG. 8, except that the counter-bores 129 inthe alumina ceramic insulator 188 have been removed. This will make itmore difficult to place gold brazed preforms 138 (not shown beforebrazing). Again, it will be understood by one skilled in the art thatcounter-bores, counter-sinks or combination and variations thereof canbe used, or alternatively, as shown in FIG. 14 no such structures areused in the insulator 188 to help locate and place the gold brazedpreforms 138 (not shown before brazing).

FIG. 15 is very similar to FIG. 8, except that the body fluid sideleadwires 118 have been replaced by biostable and biocompatible wirebond pads 133. In a preferred embodiment, these pads are drawn from asingle piece of wire 118, which extends down into the gold braze 138.

FIG. 16 illustrates an alternate method of manufacturing a nail-headedlead 118 as previously described in FIG. 15. Instead of continuouslydrawing the nail head 133 as a continuous piece of the leadwire 118,FIG. 16 illustrates that the nail head 412 may be machined as a separatestructure and then gold brazed 422 to the lead 118. Gold braze 422 wouldtypically be a co-brazing operation at the same time gold brazes 138 and140 are formed. As previously described, sputter layers 150,152 are notshown for simplicity.

FIG. 17 illustrates that the nail head 410 may be modified to have anelongated piece that engages the gold braze preform. This aids incentering and aligning the nail head 412 with the lead 118.

In FIG. 18, one can see that a counter-bore may be included within themachine nail head 412 into which the lead 118 protrudes. Again, thishelps with alignment during the gold braze flowing operation 422.

FIG. 19 is very similar to FIG. 18, except that in this case, thecounter-bore and nail head 412 is smaller and that a protrusion orextension is formed on the end of lead 118 to engage counter-bore 418.Again, this is to help with maintaining alignment during the gold brazereflow operation 422.

FIG. 20 illustrates that the nail head 412 may have a semi-circular (orother) shape. The advantage of the semi-circular shape is that thisincreases the wetting and sheer area to the gold braze 422 and alsoincreases the gold braze contact area to the lead 118. This contact areacan be further increased by using a larger gold preform 422, asillustrated in FIG. 21. Referring back to FIGS. 16 through 21, it willbe appreciated that a weighting fixture (not shown) may be applied tothe top of any of the nail heads or even an alignment fixture so thatthey are properly held in place during the gold braze reflow 422.

FIG. 22 is very similar to FIG. 8, except that the ferrule structure 122has been completely eliminated. By eliminating the ferrule, oneeliminates a significant amount of cost. Typically, these titaniumferrules are machined out of a solid piece of titanium, which entails asubstantial amount of machining time, labor and scrap. Referring to FIG.22, one can see that the AIMD housing 102 has been bent down to form anaperture 428 into which the hermetic seal insulator 188 is aligned. Theinsulator 188 is then gold brazed 140 directly to the AIMD housing 102.This is actually co-brazed along with gold braze 138 as previouslydescribed. It will be appreciated that instead of gold brazing directlyto the entire AIMD housing 102, the gold braze 140 may be done to a lidor a shield assembly, which is subsequently laser welded into the AIMDhousing 102 (not shown). Referring once again to FIG. 22, one can seethat on the left side, a low cost insulated leadwire 118′ has beenco-soldered 410 on the inside diameter of the feedthrough capacitor topin 117. On the right-hand side of FIG. 22, towards the device side, onecan see an alternative low cost leadwire 118′ wherein, the insulation123 can be added later. It will be appreciated that the length ofleadwire 118′ can be of any suitable length to reach a circuit board oreven provide for a stress-relieving or strain-relieving loop. Theinsulation 123 on the right side of FIG. 22 can be an insulation sleeve,an insulation tubing or even a heat-shrink tubing, which is added later.A preferred material would be an insulative tubing consisting of KAPTON.

FIG. 23 is the same as FIG. 8, except that the low cost leadwires 118′,instead of being stranded, are solid wire stubs. The lengths of theseleadwire stubs 118′ vary in length below the feedthrough capacitor 124in accordance with the application. For example, if the customer wasgoing to install a very thin flex cable to make the connection betweenleadwires 118′ and a circuit board 126 (not shown), then the leadwires118′ need not stick out very far. However, if a circuit board was beingplaced adjacent the feedthrough capacitor 124 with via holes (notshown), then it might be necessary to make the leadwire stubs 118′ alittle longer.

FIG. 24 seems similar to FIG. 8, but it also incorporates all theimportant advantages previously described for internally groundedcapacitors shown in FIGS. 5, 6, 7 and 7A. Referring back to FIG. 6, onecan see that an internal ground pin 118 gnd was provided by co-brazingit into a peninsula 139 of ferrule 122. Instead of machining a peninsula139 out of the titanium ferrule, a gold braze moat 138, 140, 408 isprovided, wherein the brazes 138 and 140 are connected by the braze moat408. One will appreciate that when viewed isometrically, this gold brazemoat could have the very same appearance as a peninsula 139 aspreviously described in FIG. 6. One will appreciate that this peninsulacould have rounded or square edges or the like. (In other words, it neednot look identical to that previously illustrated in FIG. 6). Also,there could be a number of these peninsulas, particularly for a long,rectangular part in order to provide a low impedance connection to thefeedthrough capacitor internal ground electrode plates. It will also beappreciated that these peninsulas could alternate along the left andright sides of a long rectangular internally grounded feedthroughcapacitor. Again, this is in order to make sure that the impedance ofthe internal ground electrode plate are kept low, such that a high levelof filter performance known as insertion loss can be achieved for eachactive pin. Referring back to FIG. 24, one will see that leadwire 118gnd has been extended into the body fluid side. As previously noted,typically it is not necessary to provide a grounded lead on the bodyfluid side. However, for certain AIMD abandoned lead port applications,for magnetic resonance imaging, a ground lead provided to the headerblock could be a very convenient way of dissipating energy from anabandoned lead or a defective lead. For a more thorough explanation, oneis referred to U.S. Patent Publication 2014/024,3944, entitled HEADERBLOCK FOR AN AIMD WITH AN ABANDONED LEAD CONNECTOR CAVITY, the contentsof which are incorporated herein by reference. The feedthrough capacitor124 of FIG. 24 is internally grounded, as previously described in FIGS.5, 6 and 7. It also has all of the intended advantages previouslydescribed in FIGS. 5, 6 and 7. Referring to FIG. 8, one can see that thecapacitor outside diameter metallization 132 has been completelyeliminated. The capacitor outside diameter or perimeter electricalconnection 148 to the ferrule has also been completely eliminated. Aspreviously described, not only does this reduce many expensivemanufacturing operations and eliminate expensive materials, but it alsoallows the capacitor body 124 to mechanically float from the ferrule122. This is important during subsequent customer laser welding 128 ofthe filtered feedthrough subassembly 189 into the AIMD housing 102 asillustrated in FIG. 8. The capacitor 124 will be much less sensitive tothe heat pulse (thermal shock) created by this laser welding 128 sinceit is not thermally isolated and also mechanically isolated. In otherwords, there are mismatches in the thermal coefficient of expansion ofthe ferrule 122 and the ceramic dielectric 124 itself. The insulativewasher 206 is preferably a thin washer, which is somewhat flexible;thereby, mechanically isolating the capacitor even further. In anembodiment, the insulative washer 206 would comprise an adhesive washerof polyimide. Polyimides form ring molecules, which are very stressabsorbing as opposed to epoxies, which form very long chain molecules.Accordingly, a polyimide washer 206 would be very stress absorbing. Onthe device side, as shown in FIG. 24, one can see a low cost groundleadwire 118′gnd, which is routed to a circuit board (not shown). Thisground wire 118′gnd is optional, but does provide a very convenient wayof providing an AIMD housing ground 102 for the circuit boardelectronics. This is important where the can is to be used as anelectrode, perhaps an implantable defibrillator application. In the casewhere the hermetic seal terminal subassembly 189 and the correspondinginternally grounded feedthrough capacitor are long and rectangular (forexample, a 12-pin device), then multiple ground pins 117 gnd would berequired. This would result in multiple peninsulas 138, 140, 408 thataccomplish a low impedance electrical grounding of pin 117 gnd toferrule 122. Each one of these multiple locations could be associatedwith a device side low cost ground lead 118′gnd, however, typically,only one such wire 118′gnd is required to connect to a circuit boardground trace (not shown). In other words, if there were multiple groundpins 117 gnd, typically, in only one location would there be a groundleadwire 118′gnd connected to the circuit board and the otherfeedthrough capacitor grounded via holes would simply be filled withsolder without any leadwire directed to the device side at all.

Referring once again to FIG. 24, in comparing it to the prior art, asillustrated in FIG. 2, one can see that there are many advantages. Someof these advantages include: 1) elimination of the expensive platinum orpalladium leadwires 118′ that extend from the circuit board 126 to thedevice side of the feedthrough capacitor 124 with replacement low costleadwires, such as tin-copper or insulated tin-copper; 2) elimination ofthe relatively expensive electrical connection material 148 shown inFIG. 4B, which in the prior art generally is a thermal-settingconductive polyimide; 3) elimination of the outside capacitormetallization 132. By replacing the rather lengthy leadwires 118 withthe short pins 117, one has also designed the device of FIG. 24 forrobotic assembly (automation). A robot can place the adhesive washer 206over the short pins 117 and a robot can also place the feedthroughcapacitor 124. The solder preforms 410 could either be threaded by robotor by hand over leadwires 118′ or then inserted into the feedthroughcapacitor via holes as shown. Then either a conveyor belt or a batchprocess is used to reflow the solder preform without the need forrepetitive processes. It has been found through experimentation that themanufacturing yield of the product, as illustrated in FIG. 24, is in thehigh 99% range. This is an increase in manufacturing yield of greaterthan 5% compared to the prior art technology illustrated in FIGS. 4A and4B. Another important advantage that is not really apparent from FIG. 24is that it is completely and easily reworkable. The most expensivesubcomponent in FIG. 24 is the hermetic seal subassembly 189. It hasgold brazes, which are expensive; sputtering, which is expensive: and analumina insulator, which is expensive. In addition, the ferrule itself122 tends to be very expensive. It is common practice after thesubassembly 116 is formed to do extensive thermal, mechanical andelectrical testing before this subassembly 116 is shipped to a customerfor installation into an AIMD housing 102. This includes elevatedtemperature voltage application otherwise known as burn-in and the like.There is usually some infant mortality in the capacitor population 124′,meaning that there is a yield associated with this high reliabilityelectrical and mechanical pre-screening. If the capacitor 124 does failelectrically or fails one of its insulation resistance tests, it iseasily removable by simply heating it up. In other words, all one has todo is reflow the solder preform 410 and then remove the capacitor fromthe insulative washer 206 and simply install a new feedthrough capacitorand reuse the hermetic seal subassembly. This is an enormous advantageof the present invention.

Referring once again to FIG. 2 and the length of device side leadwires118′, one can appreciate why it has never been possible to automate theplacement onto the hermetic seal subassembly 189, the feedthroughcapacitor insulation washer 206 and the feedthrough capacitor 124itself. It is because the device side leadwires are so long that theyare not rigid and it is literally impossible to keep the tolerance suchthat they will point perfectly straight. On the other hand, referring toFIG. 24, one can see that the relatively short pins 117 are alsopointing straight and rigid. Accordingly, one can appreciate that theassembly of FIG. 24 is readily built by robots and is completelydesigned for automation. It is only the last step, which involvesplacement of low cost leadwires 118′ that a human hand may be required

FIG. 24A is one possible schematic diagram of the filtered feedthroughassembly 116 of FIG. 24. Referring to FIG. 24A, one can see that theground pin 118′gnd extends from the body fluid side all the way to thedevice side. One will also appreciate that any number of activeleadwires 118′ are possible from monopolar to bipolar to tripolar . . .all the way to “n” number of active leads. One will also appreciate thatthe telemetry pin T is optional or may even embody a multiplicity of RFtelemetry pins T. In general, the telemetry pin or telemetry pins arenot associated with a feedthrough capacitor active electrode 116, 124.

FIG. 24B is almost the same as FIG. 24, except the body fluid sideground lead 118 gnd has been eliminated. In most AIMD applications, itis not necessary to provide an implanted lead conductor that has thesame potential as the AIMD housing 102. Referring once again to FIG.24B, one can see that the gold braze preform 138, 140, 408 has coveredthe top on the body fluid side of the short lead pin 117 gnd. Referringonce again to FIG. 24B, one can see that the schematic previouslydescribed in FIG. 7A could apply. Referring to FIG. 7A, one notes thatthe device side ground pin 118 gnd does not extend to the body fluidside. Again, any number of active pins are possible and the telemetrypin is optional.

FIG. 24C illustrates a green ceramic bar 188 illustrating that fourhermetic insulators are disposed on the bar. It will be appreciated thatlarger bars may include many more insulators, such as 10, 100 or “n”insulators. Referring once again to FIG. 24C, one can see that in thegreen bar there are holes 402 that are formed by drilling, punching orequipment operations. There is also a mil-slot 403 as indicated. Itshould be stated that a green bar includes the alumina ceramic andbinders and solvents. The green bar is easily handled, molded, machined,etc. If one were to grasp the bar of FIG. 24C, one could flex it backand forth somewhat. Prior to sintering, it's important to remove thefour separate insulator structures, as will be further explained.

FIG. 24D illustrates the top view of the device side of the bar of FIG.24C.

FIG. 24E illustrates the opposite side of the green bar of FIG. 24C. Theshallow slots 403 do not appear on the body fluid side.

FIG. 24F is taken from section 24F-24F from FIG. 24D illustrating theslot 403 in cross-section. As will be further explained, the slot 403becomes a very important and low cost way of providing for internalground connection to an internally grounded feedthrough capacitor.

FIG. 24G is taken from section 24G-24G from FIG. 24D illustrating thecross-section of one of the holes 402.

FIG. 24H illustrates the green bar of FIG. 24C with a mil-punched or cutbraceway 404. This shows each one of the four hermetic seal insulatorsabout to be cut out of the overall green bar 400. After the operation ofFIG. 24H is completed, we now have four separate individual insulatorsthat are ready for sintering. In general, sintering of these aluminaceramic insulators would be accomplished by a binder bake-out in whichthe temperatures are fully raised until solvents and binders arereleased and then the sintering process causes the green alumina ceramicto become fired into a hard, monolithic structure. In general, aluminaceramic insulators for human implant applications have to be of veryhigh purity so that they can withstand exposure on the body fluid side.Purities of >99% alumina are typical in the industry. Referring back toFIG. 24H, the four insulators are shown for illustration purposes only.It will be appreciated that the bars 400 can be of any size and containany number of insulators.

FIG. 24I illustrates one of the four insulators of FIG. 24H after it'sbeen sintered and sputtered. Sputter layers 150 and 152 include awetting and an adhesion layer such that the alumina insulator 188 willaccept a gold braze. The inside of the twelve through-holes 186 havealso been metallized. Referring back to FIG. 24I, the body fluid side isdirected upward.

FIG. 24J illustrates the same insulator as FIG. 24I, except in thiscase, the device side is oriented upward. Importantly, one can see thatthe slot 403 has also been sputtered or metallized with wetting andadhesion layers 150,152.

FIG. 24K is very similar to FIG. 24J, but illustrates that more than oneslot can be used. In the example shown in FIG. 24K, there are threenovel sputter slots 403, 403′ and 403″. Filter design engineers familiarwith internally grounded capacitors will appreciate that it is importantto have a ground location relatively close to the active pins or activevia holes 186. If one of these holes gets too far from ground, theinsertion loss with filter performance will be compromised. Accordingly,it will be appreciated that any number of ground points 403 or groundslots 403 can be provided up to “n” number of ground points.

FIG. 24L illustrates the insulator structures illustrated in FIG. 24Iand FIG. 24J, placed into, partially within or onto a ferrule 122. Agold braze pre-form 140, 140 s is added around the perimeter of theinsulator and gold braze pre-forms 148 are also placed around each ofthe body fluid side leadwires T and 118A through 118K. In this case,there is a telemetry pin T that will not be filtered and all of theactive leadwires 118A through 118K will be filtered.

FIG. 24M is a sectional view taken from section 24M-24M from FIG. 24Lillustrating the grounding slot 140 s in cross-section which comprises agold braze. As can also be seen, the rest of the insulator perimetergold braze is formed to ferrule 122. Sputter layers 150 and 152 havebeen omitted for clarity, but will be appreciated that they would bepresent. This gold braze 140, 140 s forms relatively mechanically robustand hermetic seal between the ferrule and the insulator 188. At the sametime, gold braze pre-form 138 around each of the leads form a strongmechanical and hermetic seal between the insulator 188 and each of theleads T,118.

FIG. 24N illustrates the hermetic seal subassembly 189 of FIG. 24inverted and rotated. In this case, one can see that there are two-partpins in accordance with the present invention, illustrated as 117 athrough 117 k. The telemetry pin can also optionally be a two-part pinin accordance with the present invention. Referring once again to FIG.24N, one can see the top view of the gold braze pedestal slot 140 s.Referring back to FIG. 6, one can see the prior art machined pedestal139 for convenient attachment of an internally grounded capacitor 124.As will be further described, the gold brazed slot 140 s will contactthe internally grounded capacitor internal electrode plates. The novelgold braze slot provides a much lower cost convenient alternative toproviding a pedestal 139 as previously illustrated in FIG. 6. Referringonce again to FIG. 24N, one can see a dashed line 401 that separates thegold braze in the slot 140 s from the perimeter gold braze 140. Theinventors have found that when one attempts to gold braze both the slotand the full perimeter of the hermetic seal at the same time that goldmay flow out of the slot area to where it gets too thin. Accordingly, atwo-step process may be used wherein, a pure gold or a highertemperature gold braze is first formed 140 and then in a subsequent goldbrazing operation, a lower temperature gold braze or even a lowertemperature braze of other materials, like CuSil or TiCuSil, can beplaced into the slot area 140 f. These materials need not bebiocompatible since they are on the device side not the body fluid side.The important thing is that they be highly conductive and resistant tooxides.

FIG. 24O is a sectional view taken from section 24O-24O from FIG. 24Nillustrating the novel grounding slot 140 s in cross-section.

FIG. 24P illustrates an internally grounded capacitor 124′ mounted tothe hermetic seal subassembly previously illustrated in FIGS. 24N and24O. The active electrode plates 124 of the internally groundedcapacitor 124′ are connected to the via hole metallization 130. Theground electrode plates 136 are connected to the ground via holemetallization 130G which is electrically connected to the internallygrounded capacitor's ground electrode plate set 136. It is important tonote that the ground electrode plate set for internally groundedcapacitor does not extend to the outside perimeter or diameter of thecapacitor 124′. Instead, the internal grounding is by a BGA, solder orthermal-setting conductive adhesive connection 202 directly to the goldbraze slot 140 s as shown. The gold braze slot 140 s makes a verymechanically robust, but more importantly, a very low resistanceconnection to the titanium ferrule 122. As previously mentioned, it isimportant to have connection to a non-oxidized surface. Titanium, suchas the titanium of ferrule 122, can form oxides, which can be resistiveor semi-conductive. The gold braze 140 burns through these oxidesaccomplishing a very low impedance electrical connection to thecapacitor's ground electrode plates 136. As previously described,depending on the number of active pins and their spacing, a number ofnovel gold braze slots 140 s could be provided, including ‘n’ numberslots as provided as previously illustrated in FIG. 24K elements 403. Itshould be noted that FIG. 24P is a cross-section taken generally throughthe insulator of FIG. 24N cutting generally along the line 24O-24O,except that in this case, the section has been altered such that, boththe slot 140 s and one of the active pins has been picked up. It will benoted that the internally grounded feedthrough capacitor 124′ was notillustrated in FIG. 24N, but has been added in cross-section to FIG.24P.

Referring once again to FIG. 24P, one can see that a device side, verylow cost leadwire 118′gnd can be co-connected or co-soldered at the sametime that the electrical connection 202 is made. The same is true on theactive lead 118,118′. In accordance with the present invention, there isa two-part pin consisting of 118 and 117. In this case, the novelco-brazed or co-welded short pin 117 (platinum, palladium or nickel orthe like) is shown flush with the insulator surface, such that anelectrical connection 202 can be made, as previously described for theground connection side including attachment of a device side groundleadwire 118′gnd. In the case of the active pins or active leadwires118′, which will be routed to AIMD electronic circuits or circuitboards, not illustrated. On the body fluid side, in general, there isnot a need for a ground pin. So on the body fluid side, as previouslydescribed in FIG. 24N, there is a telemetry pin T along with active pins117 a through 117 k. Each of these active pins are associated with itsown active electrode plates, as previously described in FIG. 5.Referring once again to FIG. 24P, one can see that the hermetic sealsubassembly, including the internally grounded feedthrough capacitor124′ has been laser welded 128 into the housing 102 of an activeimplantable medical device. One can see from the curvature of thehousing 102, that in general, the feedthrough capacitor 124 is disposedon the device side, which means that it is contained within thehermetically sealed and overall electromagnetically sealed AIMD housing102.

Referring now back to FIG. 8 and comparing it to FIG. 24P, one can seesome very important advantages of the internally grounded capacitor124′. In FIG. 8, the conventional feedthrough capacitor 124 has anexternal metallization or perimeter metallization 132 and acorresponding electrical connection 148. Both of these elements 132 and148 have been eliminated in FIG. 24P. Elimination of these connectionshas many advantages, including protection of the relatively sensitivefeedthrough capacitor 124′ from thermal shocks imposed by laser welding128 of the completed assembly of the housing of an AIMD.

FIG. 24Q is taken from section 24Q-24Q from FIG. 24P illustrating ablow-up of the internally grounded capacitor's ground connection to thegold braze grounding slot 140 s. One can see that the BGA material,which can be, of course, of solder or of thermal-setting conductivematerial, has been reflowed such that it makes a strong mechanical andelectrical connection both to the gold braze slot 140 s and to thedevice side ground leadwire 118′gnd. Importantly, there is also anelectrical connection made at the same time to the capacitor's throughhole metallization 130 as shown. As previously described, the low costleadwire on the device side 118′gnd, will have a very high pull strengthsince much of the electrical connection material 202 is in shear both tothe lead 118′gnd and to metallization surface 130. Also, in this sectionone can see that the ground leadwire 118′gnd has a tinned surface 115,which helps material 202 flow thereby increasing pull strength andreliability.

FIG. 24R is an exploded view taken from FIG. 24P illustrating that theBGA connection 202 may be dispensed by a robot or by human hand on thehermetically sealed insulator 189 or alternatively to the internallygrounded feedthrough capacitor 124′ or in some embodiments, to both.Shown is an adhesive insulating washer 206. It will be appreciated thatthese elements will be brought together and co-attached in a hightemperature process which bonds in the adhesive of washer 206 and eithersubsequently or at the same time, reflows solder BGA connection 202 orthermal-setting conductive adhesive or cures thermal-setting conductiveadhesive 202.

FIG. 24S and FIG. 24T are very similar to FIGS. 24P and 24R, except inthis case, instead of a gold braze slot 140 s, a peninsula structure 139is very similar to that described in FIG. 6, is shown. This peninsulastructure 139 would generally be machined out of the same block oftitanium that also forms the ferrule 122. As had been previouslydescribed, titanium can form oxides or even tri-oxides, which can bevery resistive. Connecting to titanium could preclude the properinsertion loss (filter performance) of the feedthrough capacitor 124′.Referring once again to FIG. 24S, one can see that there is a novelcounter-bore 139 g into which a gold braze preform 180 d is placed. Ingeneral, gold brazed preform 140 d would comprise a small dot, arectangle, a slot or any other shape. Gold braze preform 140 d wouldgenerally be reflowed in a gold braze furnace at the same time that theinsulator 188 gold braze to ferrule 140 is formed and also gold braze138, which hermetically seals and co-joins device side leadwire 186 topin 117. Importantly, bold braze 140 d provides a non-oxidized surfaceto which the ground electrical material 202 can be attached.

Referring to FIG. 24T, one can see on the device side of the internallygrounded feedthrough capacitor 124′, that the capacitor metallization,on the left side, has been extended onto a portion of the top of thedevice side of the feedthrough capacitor 119′. This is also known as awhite-wall tire effect and when a leadwire (not shown) is added, thisgreatly increases the pull strength. On the right side of thefeedthrough capacitor 124′ of FIG. 24T, one can see that the capacitorvia hole has been completely filled with metallization, including ametallization area on the device side of the feedthrough capacitor 119″.This provides a convenient location for soldering, for wire bonding of aribbon or a round lead 118′ that will be routed to AIMD electronics (notshown).

FIG. 24U is the schematic diagram of the internally grounded capacitorwhich was developed all the way from FIG. 24C all the way inclusive toFIG. 24T.

FIG. 25 illustrates an internally grounded feedthrough capacitor 124′ aspreviously described in FIG. 24, except that the gold braze moat 138,140, 408 has been eliminated and instead replaced by internal groundplates 137 that are embedded within a multilayer and co-fired aluminaceramic insulator 188. Sputtering of the adhesion 152 and wetting layers150 electrically connects these embedded ground plates 137 in parallel.Subsequent gold brazing operation 140 electrically connects the ferrule122 by way of this sputtering 150, 152 to the ground plates 137.Embedded ground plates within a hermetic insulator are described by U.S.Pat. No. 7,035,076, the contents of which are incorporated herein byreference. Accordingly, the internally grounded structure illustrated inFIG. 25 has all of the advantages previously described for FIG. 24.

FIG. 26 illustrates the assembly steps for the structure of FIG. 25 in amanner very similar to that previously described in FIG. 24R. A majoradvantage is the elimination of the capacitor outside diameter orperimeter metallization 132 and electrical attachment 148 to the ferrule(reference FIG. 8 electrical attachment material 148). Accordingly, FIG.26 is completely designed for automation.

FIG. 26 is the assembly of FIG. 25 showing it exploded into its varioussubcomponents. Shown is the internally grounded hermetic insulatorsubassembly 189 and the internally grounded feedthrough capacitor 124′ready to be disposed on top of the adhesive washer 206 and on top of thehermetic seal insulator 188. As previously described, this assembly canbe automated and can be reflowed in a conveyor belt, furnace process orin a bulk process, such as a DAP sealer.

FIG. 27 illustrates the exploded components of FIG. 26 after thecapacitor 124′ has been adhesively bonded 206 to the hermetic sealinsulator 189 and ferrule 122. Solder preform 410 is in place and readyto be reflowed. Attention should be drawn to another very importantadvantage of the present invention. This can be seen in FIG. 27 as thediameter or the dimension of a rectangle 125. By elimination of anyelectrical connection between the capacitor outside diameter orperimeter to the ferrule 122, the capacitor 124′ can actually be madelarger in diameter or in a rectangular dimension. This adds enormouslyto the capacitor's effective capacitance area (ECA). It should be notedthat this ECA is a square law. For example, if one were to double theoutside diameter or double the length and width, one would multiply theeffective capacitance area by a factor of four. So even a 10% addition,or 20% addition to the capacitor diameter, greatly increases itsvolumetric efficiency. It will be appreciated that instead of a solderpreform 410, one could also use a robotic or hand dispenser of athermal-setting conductive adhesive, which would be flowed down and makea similar connection.

FIG. 28 is another internally grounded capacitor 124 similar to thosepreviously described in FIG. 24 and FIG. 25. The advantage of FIG. 28 isthat the gold braze moat 138, 140 s, 408 of FIG. 24 has been largelyreplaced with a metallic piece 141 illustrated isometrically in FIG. 29.This metallic piece 141 would typically be of titanium so that it willreadily accept gold brazes 138 and 140 s. The advantage of using atitanium metallic piece 141 is that less gold is required and of course,gold is very expensive. It will be noted in FIG. 28 that in the areawhere the metal piece 141 is located, sputter layers 150 and 152 coverthis peninsula area of the hermetic insulator 188. This means that inactual production that the gold braze layer 138 would merge with thegold braze layer 140 as a very thin line of gold above the metal piece141. This is desirable since it enhances the mechanical, structural andhermetic stability of the entire package. It will be understood thatthis thin layer of gold will typically be present, but is not shown forsimplicity. It is also likely or even probable that the thin layer ofgold will partially or totally cover both the top and bottom of themetal piece 141.

FIG. 29 is a perspective view of the metallic piece from FIG. 28.Referring once again to FIG. 29, one can see that this appears to be amachined piece of material, which would typically be of titanium. Itwill be appreciated that the metallic piece 141 could also be a verythin stamped titanium metal which would make it much less expensive tomanufacture. The stamped or machined metal piece 141 of FIG. 29 offersmany advantages over the gold brazed slot 140 s illustrated in FIG. 24P.It is very difficult to maintain gold braze is it will want to wet orflow to other areas, for example, around the outside diameter orperimeter of insulator 188. The metal piece 141 prevents the gold fromflowing to areas where it is not desired, achieving the result shown inFIG. 28.

FIG. 30 is another internally grounded capacitor version. In this case,the ferrule 122 has been extended into a peninsula 139 as shown. Theferrule 122 would be machined such that, the peninsula 139 is formed.This is best understood by referring back to prior art FIG. 6 where onecan see peninsula 139. The peninsula 139 could be very similar in shape.As previously noted, there could even be multiple peninsulas andmultiple ground leads. Referring once again to FIG. 30, one can see thatthere is a short ground pin in accordance with the present invention 117gnd that has been gold brazed 138 into the peninsula 139. This providesa convenient grounding pin for contact to the internally groundedfeedthrough capacitor 124 and to ground electrode plates 136. The deviceside of the internally grounded feedthrough capacitor 124′ has beenprovided with convenient counter-sinks for placement of solder preformor thermal-setting conductive adhesives 410. It will be appreciated thatone could machine, in one piece, the ferrule 122, the pedestal 139 andthe ground pin 117 gnd. This would eliminate the ground pin 117 gnd andthe gold braze 138 g. However, now we′d be faced with a problem when theground pin 117 gnd would comprise titanium because it would oxidize.This would require a supplemental plating or sputtering operations, suchthat one could make a good electrical connection 410 to ground pin 117gnd.

FIG. 30A is similar to FIG. 40, except that the device side leads 117and 117 gnd have been extended below the surface of an internallygrounded feedthrough capacitor 124′, such that a flex cable 151 can beattached. This would normally be done in two steps where a highertemperature solder 410 makes the electrical connection between thefeedthrough capacitor metallization and the relatively short pins 117and 117 gnd of the present invention, Flex cable 151 is attached,usually by a secondary soldering operation 153 at a lower temperature.The flex cable 151 can have many different circuit traces. In this case,only two are illustrated for simplicity. These are circuit traces 155and 157. Each of the flex cable 151, circuit traces 155 and 157 isassociated with a via hole for placement over pins 117 and 117 gnd andsubsequent soldering 153. Of course, flex cables, as is known in theart, can be multilayer or quite wide and have many different circuittraces embedded within them. Flex cables are commonly used in AIMDs forconnection to an AIMD circuit board (not shown). Flex cables are alsoadvantageous since their installation can be automated and that they areinherently resistant to shock and vibration stresses.

FIG. 30B is similar to FIG. 30A, except that in this case, leadwires 117gnd and 117 have been elongated such that they can be routed all the wayto an AIMD circuit board (not shown). As previously described, since theleadwires 117 of the present invention are generally co-brazed 138 orco-welded 424 to a device side lead 118, they must be capable ofwithstanding these high temperature operations. In other words,referring once again to FIG. 30B, it would not be possible to use a lowcost device side leadwire 117 comprised of a low melting material, suchas copper or the like. In this case, a suitable material would benickel, which would probably require a supplemental tin dipping, soldercoating or plating operation.

FIG. 31 illustrates a prior art monolithic ceramic capacitor 194. Theseare otherwise known as MLCCs. Monolithic ceramic capacitors are verywell known in the prior art and are produced daily in the hundreds ofmillions. It will be appreciated that MLCCs are also commonly referredto as multilayer ceramic capacitors. MLCCs are common components inevery electronic device, including computers, modern smart phones andthe like. It should be noted here that not all rectangular 2-terminalcapacitors, as illustrated in FIG. 31, must be ceramic. As used herein,MLCC or monolithic ceramic capacitors shall also include all kinds ofstacked tantalum, stacked film and other dielectric type capacitors thatform 2-terminal rectangular shapes. It will also be appreciated that anyof the 2-terminal capacitors in the art, including ceramic, film andtantalum could also have other shapes other than rectangular, includingcylindrical and the like.

FIG. 32 taken from section 32-32 from FIG. 31, illustrates across-section of an MLCC capacitor. As can be seen, the prior art MLCCis a two-terminal device having a metallization on the left 130 and ametallization on the right 132. It has overlapping electrodes asillustrated in FIGS. 33 and 34. It has an effective capacitance area ECAcreated by the overlap of the left-hand electrodes 134 with theright-hand electrodes 136.

FIGS. 35, 35A and 35B illustrate prior applications of MLCC capacitors194 to hermetic seal subassemblies of active implantable medicaldevices. These patents include: U.S. Pat. Nos. 5,650,759; 5,896,267;5,959,829 and 5,973,906, the contents of which are incorporated hereinby reference.

FIG. 35C illustrates a prior art flat-thru capacitor. This is betterunderstood by referring to its internal electrode plates as illustratedin FIG. 35D. This is also known as a three-terminal capacitor becausethere is a circuit current that passes through its electrode plate 175from the first terminal 180. If there is a high frequencyelectromagnetic interference signal being conducted along this electrodeplate, then it comes out the other side at a second terminal 182.Referring back to FIG. 35C, there is a general disadvantage to suchcapacitors in that, at very high frequency EMI 188 can cross-couple fromthe left side of the MLCC capacitor to the right side.

FIGS. 35E, 35F and 35G illustrate a three-terminal capacitor that isalso known in the industry as X2Y attenuator. These are well known inthe prior art. It will be appreciated by one skilled in the art, thatany of these flat-thru or X2Y attenuators can be applied to the presentinvention.

FIG. 36 illustrates the application of MLCC capacitors 194 and 194′ tothe present invention. It will be noted that the left-hand device sidepin 117 a is relatively short to accommodate placement of flex cable(not shown) or a circuit board adjacent the hermetic seal insulator 188and ferrule 122 on the device side. Referring once again to FIG. 36, onecan see that the right-hand device-side leadwire 117 b has beenelongated so that it can be directly connected to an AIMD circuit board126 (not shown). An optional insulating sleeve (not shown) could beplaced over the right-hand leadwire 117 b. A disadvantage of MLCC chipcapacitors is that they are two terminal devices and have substantialseries inductance. This causes them to self-resonate at lowerfrequencies than a feedthrough capacitor. Above resonance, MLCCcapacitors become increasingly less effective as a filtering element.Accordingly, it is preferable that MLCC chip capacitors be relativelysmall in size. Reverse geometry is a popular technique, where theterminations are placed along the long sides instead of the short sides.Reverse geometry reduces the internal inductance of the MLCC capacitors194. The advantage of reverse geometry MLCCs for higher frequencyfiltering is further explained in U.S. Patent Publication 2014/0168917(look at FIGS. 16 through 18) the contents of which are incorporated infull herein by this reference.

It is also very important that in an AIMD application that the MLCCs beplaced in such a way that the electrical connections do notsubstantially increase this undesirable series inductance. Accordingly,the capacitors 194, 194′ of FIG. 36, have been placed immediatelyadjacent leadwires 117 a and 117 b at the point of entry of the AIMDhousing. MLCC capacitors do not have a polarity; therefore, they can beoriented in any direction. For the purposes of the present invention,the capacitor termination 132 will also be known as the groundtermination. This is because there is an electrical connection 143between the capacitor ground termination 132 and the ferrule 122 and itscorresponding gold braze 140. Connection to the gold braze is importantsuch that a very low impedance, non-oxidized connection is made. Theactive side of the MLCC chip capacitors is denoted by terminationmaterial 130. There is an electrical connection 145 that is made betweenthe active termination 130 and the corresponding leadwires 117 a and 117b. Referring once again back to FIG. 36, electrical connection materials143 and 145 can include a wide range of thermal-setting conductiveadhesives, including conductive epoxies and conductive polyimides. Thereis also a wide range of solders and low temperature brazes that alsocould function as these electrical connections.

FIG. 37 illustrates a modified hermetic terminal. In this context,modified means that the gold braze 140 is disposed towards the bodyfluid side instead of towards the device side. This makes it difficultto perform an oxide-free electrical attachment 143 to the gold braze138. Accordingly, an oxide-free metal addition 149 has been added.Typically, this metal addition is laser welded 151 to the ferrule 122.It could also be brazed to the ferrule 122. Importantly, the oxide-freemetal addition 149 is a high temperature non-oxidizing material thatwill readily accept the electrical connection material 143 that makescontact to the capacitor ground metallization 132. Oxide-free additionsto AIMD ferrules have been described in U.S. Pat. Nos. 9,108,066 and9,427,596 and U.S. Patent Publication 2014/0168917, the contents of allof which are incorporated in full herein by these references.

FIG. 38 is one exemplary possible electrical schematic of the overallfiltered feedthrough assembly 116 previously illustrated in FIG. 37.FIG. 37 is a cross-sectional view showing only two leads 117. If thispart was long and rectangular, it could have 8, 9, 10, 12 or any numberof leads. If it was round, it could also have any number of leads. FIG.38 illustrates that the filtered feedthrough assembly 116 of FIG. 37,could be quadpolar. In other words, having four MLCC chip capacitors 194through 194′″.

Referring once again to FIG. 38, one will see that the electricalschematic for the MLCC capacitors 194 is different indicating that theyare two-terminal devices. In other words, the leadwire 118, 117 does notpass through the capacitor. A schematic for three-terminal orfeedthrough capacitors is shown in FIG. 24U where one can see that theactive leadwires consist of segment 118, 117 and 118′a and these passright through the feedthrough capacitor. The thing that reallydistinguishes feedthrough capacitors as three-terminal devices is thatthey generally have a through hole compared to MLCC capacitors which donot.

FIG. 39 is a cross-sectional drawing of a filtered feedthrough hermeticassembly 116 wherein, a single MLCC chip capacitor 194 is used,connected between an internal ground pin 117 gnd and an active pin 117(both on the device side). The cross-section of FIG. 39 is unipolarmeaning that there is only one active lead 118 a, 117. There is also aground lead 117 gnd. This lead 117 gnd is grounded through embeddedground plates 137 in the hermetic insulator, as previously described inFIG. 27. As can be seen, the capacitor ground metallization 132 isconnected to the grounded leadwire 117 gnd with electrical connectionmaterial 143. The MLCC capacitor active termination 130 is alsoconnected using electrical connection material 143 to active lead 117.

FIG. 39A is the electrical schematic of the filter feedthrough assembly116 of FIG. 39. Illustrated on the device side is the ground lead 117gnd and also the single (unipolar), active leadwire labeled 118 a on thebody fluid side and 117 on the device side. Also shown is the unipolaror single MLCC capacitor 194. Referring once again to FIG. 39, one cansee that the MLCC capacitor 194 is first mounted to a circuit board 147.

FIG. 40 is very similar to FIG. 39, except that the circuit board 147has been eliminated and the MLCC capacitor 194 has been directly mountedto the insulator 188 of the hermetic seal subassembly 189.

FIG. 41 is very similar to FIG. 2 in that, it shows the interior of anactive implantable medical device 100C. In this case, it would betypically a cardiac pacemaker. It will be known to those skilled in theart that this prior art figure could apply to any type of AIMD. A wirebond board 153 is shown attached adjacent to a feedthrough capacitor 124which is in turn, attached to the ferrule 122 of a hermetic sealfeedthrough assembly. One is referred to U.S. Pat. No. 7,038,900, FIGS.75 to 77 for a more complete description of the wire bond board 153. Thecontents of the U.S. Pat. No. 7,038,900 patent are incorporated hereinby reference. One is also referred to U.S. Patent Publication2014/0168917, the contents of which are incorporated herein and areknown as the '917 Publication. FIGS. 42 through 46 herein are similarwith FIGS. 21 to 25 of the '917 Patent Publication. FIGS. 21 to 25 ofthe '917 Patent Publication do differ from FIGS. 41 through 46 herein,in that, in the present invention, there are four (quadpolar) activewire bond pads 169 a through 169 d and a ground wire bond pad 169 gnd.The ground wire bond pad 169 gnd is at the same electrical potential asthe ferrule 122. One can see that the wire bond board 153 is generallyadjacent to the hermetic seal ferrule 122 and is disposed on the deviceside. FIGS. 44 through 46 illustrate that the wire bond pad board 153 ofFIGS. 42 and 43 may be multilayer. FIG. 44 illustrates that there may beinternal circuit traces 155 that are built up in sandwiched layers. FIG.45 illustrates that an internal layer may contain embedded MLCC chipcapacitors 194, which connect 130 from each of the active quadpolarleads to ground 132, 122 and thereby act as filters. It will beappreciated that these chip capacitors 194 have been previouslydescribed in FIG. 37 and generally connect from the active (quadpolar)leadwires or pins at MLCC capacitor termination surface 130. It willalso be appreciated, in FIG. 45, that the opposite termination ormetallization 132 of the MLCC capacitor 194 is connected to ground 122(through an internal circuit trace via that electrically connects to theferrule potential that is not shown). Referring back to FIG. 43, onewill appreciate that on the body fluid side, the leadwires are labeled118 and in accordance with the present invention inside of a hermeticinsulator 122, leadwire 118 is co-joined by welding or co-brazing to thedevice side leadwire 117. Once again, referring to FIG. 45, one will seethat the embedded MLCC capacitors 194 could be discrete components, butcould also be laid out in discrete layers with active and groundelectrode plates as the multilayer board itself is filled up. FIG. 46illustrates that one or more cover sheets 156 may be added on top of themultilayer board of FIGS. 44 and 45, thereby embedding the MLCC chipcapacitors 194 entirely within the board. This embedded technology isgenerally known in the prior art. It will also be appreciated and shownin subsequent drawings that the MLCC chip capacitors 194 need not beembedded in the board, but could be surface mounted on its device side.It will be appreciated that any of the wire bond boards described inFIGS. 41 through 46 can be applied to any of the embodiments of thepresent invention.

Referring once again to FIG. 43, one can see that the leadwire 118 onthe body fluid side, is labeled 117 on the device side. This is inaccordance with the present invention. It will be appreciated that theleadwire in accordance with the present invention, could be co-welded orco-brazed within the hermetic seal insulator (not shown). It could alsobe co-joined within the wire bond block 153. In another embodiment, thebody fluid side leadwire 118 could be co-joined in the insulator to ashort pin segment 117 as shown. In general, the body fluid side leadwire118 would be of a different material than the device side leadwire 117.It will also be appreciated that wires would be attached to pads 169 athrough 169 d either through wire bonding or the like and these wireswould be routed to AIMD circuits (not shown).

FIG. 47 includes a circuit board 147 which is adjacent the hermeticferrule 122 and hermetic insulator 188. FIG. 47 is taken from FIG. 35 ofthe '917 U.S. Patent Publication. FIG. 47 does incorporate the presentinvention in that, the body fluid side lead 118 has been co-brazed 138with the device side lead 117. One will note that these two have beenwelded 424 together prior to the brazing operation in accordance withthe present invention. As can be seen, the circuit board 147 isco-bonded to the ferrule 122 and insulator 188 with an adhesive washer206, which is considered optional. It will be appreciated that there area wide variety of ferrules and hermetic insulators that are used in theAIMD industry. It is not in all cases that the insulator 188 is adjacentor is aligned at the top of the ferrule. In this case, it is appreciatedthat the circuit board may be bonded to the ferrule, the insulator orboth. The circuit board 147 includes one or more circuit traces 157 toAIMD electronics. Referring once again to FIG. 47, it will beappreciated that board 147 may be single layer, as shown, with circuittraces 157 on its top (device side). It will be further appreciated thatboard 147 could be multilayer and the circuit traces 157 could beembedded within the board. In the case where there are a number ofleadwires 118, for example, 10 or 12 leads, then it would be preferablethat the board 147 be wide and multilayer thereby incorporating a numberof circuit traces on its top surface and on multiple layers (not shown).

FIG. 48 is taken from FIG. 55 of the '917 U.S. Patent Publication. Inthis case, there are two embedded circuit traces 157 and 157′. There isalso a surface mounted MLCC chip capacitor 194, as was previously shownin FIG. 47. The MLCC capacitor 194 decouples undesirable electromagneticinterference (EMI) signals from lead 118, 117 and diverts it to theferrule 122 and in turn, to the AIMD housing 102 (not shown). Thesectional view shown in FIG. 48 again, embodies the present invention,including body fluid side biocompatible leadwire 118, which is co-brazed138 to the device side leadwire 117. Again, in this case, they arepre-joined (optionally) by welding 424 in accordance with the presentinvention. Referring once again to FIG. 48, one can see that thishermetically sealed filter assembly appears to be unipolar. However, itcan be multipolar, such as bipolar, tripolar, quadpolar or the like (allthe way to “n”-polar). Embedded circuit traces within the circuit boardmay be both routed to a unipolar pin or preferably multiple circuittraces that are embedded in the circuit board could be routed each tomultipolar pins, such that the multipolar pins are each associated withan MLCC capacitor 194 . . . 194 _(n) and are associated with individualcircuit traces 157 . . . 157 _(n). Circuit board 147 could be a rigidcircuit board, such as FR4 board, alumina ceramic or the like. Circuitboard 147 could also be a flex cable, which is well known in the art.

FIG. 49 is taken from the '917 Patent Publication, FIG. 37. The hermeticseal assembly 116 is octapolar, meaning that it has 8 pins. Seven ofthese pins are active and one is a telemetry pin T, which as previouslydescribed, has to be unfiltered. Each one of the active pins 117 athrough 117 g are each associated with an MLCC chip capacitor 194 athrough 194 g, which act as EMI low pass filters, which can also becalled RF diverter elements. Capacitors are grounded to an oxide-freemetal addition 159, which is in turn is laser welded 173 to the ferrule122. FIG. 49 is very similar to FIG. 48 of U.S. Patent Publication2014/0168917. The function of the metal addition 159 in performing anoxide-resistant low impedance ground connection from the ferrule 122 tothe MLCC capacitor ground terminations 132, is more fully described inthe '917 patent publication. Typically, this metal addition 159 could beof platinum or palladium or the like. This facilitates easy welding tothe ferrule 122 while at the same time, has excellent solderability.Accordingly, an electrical attachment material 143 can comprise ofsolder, a thermal-setting conductive adhesive or the like. It will alsobe appreciated that the metal addition 159 can be eliminated if thecapacitor ground terminations are electrically connected 143 directly tothe gold braze area 140. The importance of grounding a feedthroughcapacitor or MLCC chip capacitor to an oxide-free connection is morethoroughly described in U.S. Pat. No. 6,765,779, the contents of whichare incorporated herein by reference.

Referring once again to FIG. 49, one can see that the body fluid sidepins are labeled 118 a through 118 g and are generally biocompatible andnon-toxic. The leadwire segments are drawn on the device side as 118′athrough 118′g and in accordance with the present invention, embody adifferent material than the body fluid side leads. Referring once againto FIG. 49, it will be appreciated that the ground side 132 of the MLCCcapacitors 194 could embody a circuit trace running all along the leftside of the board with one or more attachments either directly to thegold braze 140 and ferrule 122 or through a metal addition 159, aspreviously described.

FIG. 50 is taken from section 50-50 from FIG. 49. Another differencebetween FIG. 50 and FIGS. 47 and 49 are that the gold brazes 140 and 138are now disposed to the body fluid side instead of to the device side.Importantly, the gold braze 138 flows around both the body fluid sidepin 118 and the device side pin 117, thereby effecting a mechanicallystrong hermetic seal connection. Having gold braze 138 surround bothpins or leadwires 118 and 117 is important such that a strong sheerconnection is created. This makes for a relatively high pull strengthfor both the body side lead/pin 118 and the device side lead/pin 117. Itshould be noted throughout this patent, in general, when referring tothe pin in a hermetic seal or in a feedthrough capacitor that this pincan also be referred to as a lead or a leadwire. In accordance with thepresent invention, these terms can be used interchangeably. The term“conductive pathway” could also be applied; for example, to theconductive pathway created by body fluid side pin 118 to device side pin117 of FIG. 50. Again, the circuit board 147 could be rigid or flexibleand incorporate at least one circuit trace 157 routed to AIMDelectronics. Furthermore, the electrical

FIG. 51 describes a hexapolar (6) hermetically sealed filtered terminalin accordance with the present invention. Shown are 6 MLCC capacitors194 a through 194 f that are mounted onto circuit board 147. The circuitboard is shown in cross-section in FIG. 52, which is taken from section52-52 from FIG. 51.

FIG. 53 is a second sectional view taken from section 53-53 from FIG.51. As best shown in FIG. 52, there are two ground pins (or groundleadwires) 117 gnd that are directly co-brazed 165 into the ferrule 122as shown. One of these ground pins 118′gnd is on the far left of circuitboard 147 and the other is on the far right of the circuit board 147.

Referring once again to FIG. 52, one can see that the left side groundpin 117 gnd does not go all the way from the body fluid side to thedevice side of the ferrule 122. An alternative ground pin 117 gnd isshown on the right side. This pin 117 gnd goes all the way through theferrule 122 as shown. This pin shows both an optional counter-sink 165and a counter-bore 165′ on the body fluid side. It will be appreciatedthat counter-sink 165 could also be a counter-bore and counter-bore 165′could also be a counter-sink. It will be further appreciated that thepin could be gold brazed in without a counter-bore or counter-sink oneither side. Referring once again to the right hand side ground lead 117gnd, one appreciates that it can be gold brazed to the ferrule atlocation 165 or at location 165′ on the body fluid side.

Embedded within circuit board 147 is a ground circuit trace 161. It willbe appreciated that a plurality of internal ground circuit traces 161can be incorporated, which would further reduce the impedance betweenthe ground pins 117 gnd across the ground plane 161. In one preferredembodiment, there would be two internal ground plates 161 and anexternal ground plate disposed at or near the bottom of the circuitboard where it is adjacent to either the ferrule 122, the insulator 188or both. The active hexapolar leadwires on the device side are labeled118′a through 118′f. Each one of these are associated with an MLCCcapacitor which acts as an EMI low pass filter or diverter. Referring toMLCC capacitor 194 a in FIG. 51, one can see that on its groundmetallization side 132, it is electrically connected to ground via hole163 b. On the active termination side 130 of MLCC capacitor 194 a, youcan see a circuit trace (CT) and an electrical connection to via holeabout leadwire pin 117′a. Referring to FIG. 52, one can see the activedevice side pin 117′a running through the via hole of the circuit board147 and being co-gold brazed 138 with the hermetic insulator 188 to thebody fluid side leadwire 117 a. This is in accordance with the presentinvention. Referring once again to FIG. 51, MLCC capacitor 194 a on itsground metallization side 132 is connected through a short circuit traceor directly through soldering or thermal-setting conductive adhesives toground via hole 163 b. It will be appreciated that on either the activeor ground side of the MLCC capacitors 194, there could be a directconnection to either the via holes or pins or elongated circuit tracescould be used on one or both sides, as illustrated. It will also beappreciated that these circuit traces could embody a second via hole andthe circuit trace itself could be internal to the circuit board, as isknown in the art. Referring to FIG. 53, one can see in cross-section,the grounded via hole 163 b, which is electrically connected to theembedded ground plane or ground circuit trace 161 within the circuitboard 147. It will be appreciated by those in the art that the groundcircuit trace 161 could take on many different shapes or dimensions oreven be multilayer. For simplicity, a single layer is shown. The circuitboard 147 could be of a flex board or what's known in the art as a flexcable. It could also be a rigid board as shown. Materials for a rigidboard would include ceramic, such as an alumina ceramic circuit board orfiberglass, otherwise known as FR4 boards.

FIG. 53A is taken generally from section 53A-53A from FIG. 52. Thisshows the top view of the ground plane 161. Referring to FIG. 53A, onecan see that the ground plane 151 is connected to the left ground pin117 gnd and the right ground pin 117 gnd, which is previously shown inFIG. 52, are gold brazed or welded directly to the ferrule structure122. One ground pin, instead of two, could be used; however, this wouldincrease the impedance across the ground plane and would lead to reducedfiltering effectiveness, also known as insertion loss of the mostdistant pins. It will be appreciated that any number of ground planes117 gnd as required for proper ground plane performance can be used.Referring once again to FIG. 52, one can see that the left-hand groundpin 117 gnd is quite short and only extends a little ways above thecircuit board 137. It is typical in an AIMD applications that aninternal circuit board be properly grounded. Accordingly, on theright-hand side of FIG. 52, the ground pin 117 gnd on the device side,has been elongated so that it can extend and connect to the ground traceof an AIMD circuit board (not shown). In accordance with the presentinvention, it would be desirable that these pins on the device side beof non-oxidizable material, such as palladium or platinum. Othermaterials or alloys, such as platinum-iridium or palladium-iridium, canalso be used. On the device side, these leadwires 117′ are generallylong so that they can be routed to a distant circuit board 126 havingAIMD electronic circuits. Referring once again to FIG. 51, one can seethe second MLCC capacitor labeled 194 b. It is connected at its activetermination 130 to via hole 117 b, which is also illustrated in FIG. 52.Referring once again to MLCC capacitor 194 b, its ground termination 132is dielectrically connected to ground via hole 163 a. Referring back toFIG. 51, one can see that the MLCC capacitors 194 a, 194 b all the wayto 194 f, alternate their active connections back and forth along withtheir ground connection, which also alternate as shown in FIG. 53A. Itwill be appreciated that the hexpolar (6) filter hermetic terminal ofFIGS. 51 through 53 can be of any number of terminals, including “n”active terminals, which would embody “n” MLCC capacitors. It will alsobe appreciated that non-filtered telemetry pins T (not shown) could beadded.

The ground pins 117 gnd are also known as metal additions in accordancewith U.S. Patent Publication 2014/0168917, the contents of which areincorporated herein fully by reference. For example, one is referred toFIG. 36 of the '917 U.S. Patent Publication as showing metal addition220.

FIG. 54 is a sectional view generally taken from section 54-54 from FIG.52. This shows an important low cost alternative to running theleadwires 118′ all the way to AIMD electronic circuits. It needs to beremembered that as illustrated in FIGS. 51 through 53, that theseleadwires 118′ are generally of platinum, palladium or various alloysinvolving iridium. Shown in FIG. 54, one can have a short leadwiresegment 117 of platinum or palladium and then co-join a low costleadwire 118′a. In some cases, at least one of the ground pins 118′gndwould also be long in order to connect the AIMD housing ground to theAIMD electronic circuit board ground trace. As taught in FIG. 8, theselow cost leadwires 118′ can be of extremely low cost materials, such astin-copper wire. These low cost leadwires 118′gnd and 118′a may alsoembody an insulative material 123 as illustrated in FIG. 8, or aninsulation sleeve which can be subsequently added. Comparing FIG. 54 toFIG. 8, one can see that the connection of low cost leadwire 118′ to theshort pin 117 can be accomplished either inside the feedthroughcapacitor of FIG. 8 or within a circuit board 147, as illustrated inFIG. 54. Referring back to FIG. 54, one can see that one ideal way toco-connect the short lead pin 117 gnd to the low cost leadwire extension118′gnd, would be the use of a solder or a thermal-setting conductiveadhesive 410. As taught in FIG. 8, the solder 410 would preferably be ofa high temperature solder and it would create a shear connection aroundboth leadwires, lead pin 117 gnd and low cost leadwire extension 118′gndand at the same time, also form a shear connection on the insidediameter metallization 175 of the circuit board 147 via holes. Referringonce again to FIG. 54, one can see that there are three ground plates161, 161′ and 161″. Two of the ground plates 161 and 161′ are embeddedwithin circuit board 147. Ground plane 161″ is disposed on the bottomsurface of the circuit board 147 and is immediately adjacent the ferruleand the insulator 188. This external ground plate 161″ is important asit acts to prevent the direct radiation of a closely held emitter intothe interior of the AIMD housing. This is known as direct radiatedinterference as opposed to conductive interference. Conductiveinterference would be picked up on the body fluid side of the leads andit is the purpose of the diverter capacitors 194, to divert thisunwanted high frequency conductive interference away from the activeleadwires to the ferrule 122. Direct radiated interference couldpenetrate through the edges of the circuit board 147 and undesirablycouple to sensitive electronic circuits. Accordingly, the ground plates,especially the external ground plate 161″, has a dual purpose. That is,it acts as a shield to such direct radiated interference. It alsodesirably decreases the impedance along the ground planes such that theactive pins are more effectively filtered.

FIG. 55 is very similar to FIG. 8, except that the short lead or pin ofFIG. 8 has been eliminated. In this case, there is still a co-brazedjoint 138, which may also embody a weld 424, as shown in both FIGS. 55and 8. In this case, there is a continuous leadwire 118′, which runs toAIMD electronics generally mounted on a circuit board (not shown).

FIG. 56 is very similar to FIG. 55, except that the insulation material123 on the wire can be added as separate tubing or even a heat-shrinktubing. In addition the structure of FIG. 56 has no ferrule 122 asdescribed in FIG. 55. In FIG. 56, the AIMD housing 102 has been bentdown forming an aperture, which enables the hermetic seal insulator 188to be co-brazed 140 to the AIMD housing 102. The advantage is that therelatively high cost ferrule 122 has been completely eliminated.

FIG. 57 is very similar to FIG. 54, except the short leadwire pin orstub 117 has been eliminated and the length of the leadwire 118′ hasbeen lengthened to effect a co-braze joint in accordance with thepresent invention in the hermetic insulator 188. There is a gold brazemoat 138,140,408, which grounds the left-hand pin 118′gnd. An internallygrounded feedthrough capacitor 124′ is illustrated. Importantly, thereis no need for an external perimeter or diameter metallization 132 onthe feedthrough capacitor nor is there a need for a capacitor groundconnection 148 from the capacitor outside diameter or perimeter to theferrule 122. Optional leadwire insulation 123 is shown, as has beenpreviously described in FIG. 56. As one can see in FIG. 57, there is atleast one ground pin 118′gnd that is connected to the capacitorsinternal ground electrode plate set. In this case, the ground pin isco-brazed into a gold brazed moat 138, 140, 108. The gold braze moatprovides a very low impedance and oxide-free electrical connection toboth the ferrule and to ground pin 118′gnd.

FIG. 58 is very similar to FIG. 25 in that, the left-hand ground pin 118gnd is grounded through a gold braze joint 138 to embedded groundelectrode plates 137 within the hermetic seal insulator 188. Again, inFIG. 58, the short pin or 117 has been eliminated, as previouslydescribed in FIGS. 56 and 57. In this case, the ground pin 118′gndextends all the way through the insulator 188 to the body fluid side.This is normally not the case in prior art applications, but could beimportant for MRI applications, especially where a grounded port orsurrogate pacemaker was also incorporated.

FIG. 59 is very similar to FIG. 30 in that, the ferrule 122 has one ormore peninsulas 139 which facilitates the grounding of the left-hand pin118′gnd. Again, as previously described in FIG. 57, the short ground pin117 of FIG. 30 has been eliminated. One will appreciate, referring toFIG. 59, that the peninsula 139 could be replaced with a metal piece141, as previously described in FIGS. 28 and 29.

FIG. 60 is taken from the bottom portion of the exploded view previouslyillustrated in FIG. 9. It is noted that the feedthrough capacitor 124has been removed. FIG. 60 is known in the art as an unfiltered hermeticfeedthrough terminal. These are also known as UFTs (unfilteredterminals). It can be seen that there is a joining by co-brazing 138 oftwo different materials for the pins 117 and 118 within the hermeticseal insulator body 188. The pins can be short, as shown on the left 117or it can be elongated and directed to AIMD circuits, as shown on theright 117. Importantly, not all AIMDs require filtering. For example,there are neurostimulators that have no sense circuits and areinherently immune to EMI. For example, a cardiac pacemaker or animplantable defibrillator have very sensitive circuits that monitorcardiac activity and other biologic signals. These sensing circuits makethem relatively sensitive to emitters, such as cellular telephones thatmay embody modulation at biologic frequencies. On the other hand, aspinal cord stimulator that only produces a regular pulse, which isadjustable by the patient, is relatively insensitive to EMI and may notrequire EMI filtering at the point of ingress to pins 117 into the AIMDhousing. This is because, in general, spinal cord stimulators do nothave any biological sensing circuits that would be sensitive. Throughoutthis patent, when labeled “device side”, this means that this is theside that is generally inside of the AIMD hermetically sealed housing.In summary, FIG. 60 is to emphasize that the present invention can besold as a hermetic seal without any filtering in the marketplace. Itwill be appreciated that the UFT of FIG. 60 may provide for grounding tothe ferrule potential 122 by means of a braze moat 138, 140, 408, asshown in FIG. 24, by ground plates 137 embedded in the insulator 188, asshown in FIG. 25, by a grounding metal piece, as shown in FIGS. 28 and29 or by a peninsula 139 of the ferrule 122, as taught in FIG. 30.Referring back to FIG. 60, we have a hermetic seal feedthrough assembly189, which is attachable to an opening in the housing of an activeimplantable medical device. Assembly 189 comprises an insulator body 188defined as having a first insulator side 500 opposite a second insulatorside 502. The first insulator side and second insulator side areseparated and connected by at least one outside surface 504, 526. Thereis at least one via hole 506, 506′ disposed through the insulator bodyextending from the first insulator side 500 to the second insulator side502. It will be appreciated that any number of via holes are possible.For example, in a retinal implant, there may be several hundred viaholes. The assembly 189 of FIG. 60, including an internal metallization508, which is sputtered, deposited or otherwise adhered to the insulator188. In the present invention, the internal metallization ischaracterized as comprising two sputter layers 150 and 152. However,this could be a single metallization layer, as previously described. Theinternal metallization 502 is formed, at least partially, on the insideof the one via hole 506, 506′. Assembly 189 includes a first conductiveleadwire 118 having a first conductive leadwire first end 512, at leastpartially disposed within at least one via hole 506, 506′ and having afirst conductive leadwire second end 510 disposed past the firstinsulator side 500. Leadwires 118 can be routed to an AIMD connectorblock, an implantable lead, including lead conductors or the like (notshown). In addition, there is a second conductive leadwire 117 having asecond conductive leadwire first end 514, at least partially disposedwithin the at least one via hole 506, 506′, and having a secondconductive leadwire second end 516 disposed past the second insulatorside 502. Typically, the second conductive leadwire second end would beattached to a flex cable, circuit board, a feedthrough capacitor, othertypes of filtered capacitors and onto AIMD circuits (not shown). Thefirst conductive leadwire first end is disposed near, at or adjacent tothe second conductive leadwire first end. Optionally, the firstconductive leadwire first end may be welded 424 to the second conductiveleadwire first end. In accordance with the present invention, the firstconductive leadwire 118 is not of the same material as the secondconductive leadwire 117. As shown, there is a first braze 138 at leastpartially between the first conductive leadwire 118 first end 512 andthe second conductive leadwire 117 first end 517 and the internalmetallization 508 wherein, the first braze 138 forms a first hermeticseal separating the first insulator 500 from the second insulator side502 and a second external metallization 518 is disposed at leastpartially on the at least one outside surface 504 and insulator body188. As shown, the outside surface 504 of the insulator may be goldbrazed 140 to a conductive ferrule 122 defined as having a first ferruleside 520 opposite a second ferrule side 522 and defining a ferruleopening 524 between and through the first ferrule side 520 and secondferrule side 522 wherein, the insulator body 188 is at least partiallydisposed within the ferrule opening 524. As shown, there is a secondgold braze 140 at least partially between the external metallization ofthe insulator body 518 and the conductive ferrule body 122. A secondbraze forming a second hermetic seal hermetically sealing the ferruleopening.

FIG. 61 is very similar to FIG. 60, except that it incorporates internalground plates 137 that are contained within the hermetic insulator 188.These internal ground plates 137 facilitate the grounding of at leastone of the pins, in this case 118 gnd, 117 gnd on the right-hand side,which provides a convenient way for grounding of an AIMD circuit boardground trace.

FIG. 62 shows an alternative method using a gold braze moat 138, 140,408 for ground pin 117 gnd.

FIG. 63 illustrates that the right-hand ground pin 118 gnd can also begrounded by a co-machined peninsula 139 of the hermetic seal insulator122, as previously described in FIG. 6. Referring once again to FIGS.60, 61, 62 and 63, it shall be noted that on the device side, the pinsor 117 may be short or may be elongated and directed to AIMD circuits.When short, it would be convenient to make electrical attachment insidethe AIMD with a circuit board (not shown), a flex cable (not shown), orindividual wires (not shown).

FIG. 64 is very similar to FIG. 8, except that the pin 118′ has beenformed into a wire wrapped terminal 177. This wire wrapped terminal 177is shown proud of the device side surface of the feedthrough capacitor124.

FIG. 65 is very similar to FIG. 64, except that it shows the hermeticterminal subassembly 189 inverted and the feedthrough capacitor 124 hasbeen eliminated. This means that FIG. 65 is very similar to FIG. 61,except that the device side pin 117 has been replaced by a formed wirewrapped pin 117, 177, as illustrated in FIG. 65.

One is now directed to FIGS. 66A through 72B, which illustrate that thewire wrapped pins 118′ of both FIG. 64 and FIG. 65, may be replaced byany of these shapes to facilitate a connection to device side leadwiresor circuit boards (not shown).

FIG. 73 illustrates that the present invention, shown on the left sideembodying body fluid side pin or leadwire 118 and device side 117 wereco-joined or co-brazed 138, may comprise a hybrid structure wherein, oneor more of the conductive pathways or conductive vias through thehermetic seal insulator, has been co-fired forming a conductive via 167.Conductive vias are well known in the prior art and may comprisesubstantially pure platinum, CERMET materials, various combinations ofmetal binders and metal paste and the like. One is referred to U.S. Pat.Nos. 8,653,384; 8,938,309; 9,233,253, the contents all of which areincorporated herein by reference. Referring once again to FIG. 73, itwill be appreciated that the left side pin 117, shown on the deviceside, may be replaced by any of the wire wrapped terminals or shapespreviously illustrated in FIGS. 65 and 66A through 72B. Referring onceagain to FIG. 73, it will be appreciated that the co-firing of theconductive via 167 and the alumina insulator would be typically formedas a first step at a very high temperature. In a secondary manufacturingoperation, gold brazes 138 and 140 would be performed in a gold brazefurnace thereby, co-joining 118 and 117 while at the same time, creatinga mechanical and hermetic seal 140 to the ferrule 122 and the insulator188. Referring back to the drawing description for FIG. 8B, it will beappreciated that in FIG. 73, that the sintered paste 167 could compriseany of the material combinations previously described for FIG. 8B.

As illustrated in FIG. 74 any of the embodiments of these referencedpatents can be combined with the present invention, including a co-firedor co-sintered pin 118 that is co-fired with via fill material 167.Again, it will be appreciated that referenced U.S. Pat. Nos. 8,653,384;8,938,309 and 9,233,253 have many embodiments and any of the embodimentsof these references can be combined in other conductive pathways; forexample, as illustrated in FIG. 8, FIG. 15 and FIG. 11 herein.

FIG. 75 is very similar to FIG. 12, except that an eyelet 426 is used inplace of leadwire 118′ and its insulation 123. This eyelet can abut pin117 as shown. In both cases, the solder 410 will flow down around boththe inside and outside diameters of the eyelet and also around theoutside diameter and end of pin 117 thereby, making a very mechanicallystrong connection. As shown on the right-hand side of FIG. 75, theeyelet 426 can overlap pin 117, which would provide even more strengthdue to the solder that is in sheer between the inside diameter of theeyelet and the outside diameter of pin 117. The eyelet is designed tofacilitate convenient wire bonding by a customer. Wire bonding is wellknown in the art and could involve a round or a flat ribbon wire thatwould be electrically and mechanically connected to the device side ofthe eyelet 426 and then connect to a circuit board or internal AIMDelectronics (not shown).

FIG. 76 is taken generally from section 76-76 of FIG. 75 and illustratesthat the capacitor inside diameter or via hole metallization 130 mayextend onto the device side of the feedthrough capacitor forming awhite-wall tire configuration 411, as previously described in FIG. 12.This would allow solder 410 (or a thermal-setting conductive adhesive)to not only flow down around the inside diameter (or via hole) of thefeedthrough capacitor, but it would also flow all around the eyelet andalso form a solder joint between the bottom surface of the top of theeyelet and the white-wall tire metallization 411. As mentioned in FIG.12, this would greatly increase the mechanical strength of a connectionbetween the eyelet 426 and the feedthrough capacitor 124. Importantly,this also provides an even lower electrical resistivity between theeyelet and the capacitor metallization, and corresponding activeelectrode plates. It will be appreciated that the white-wall tirestructure 411, as illustrated in FIG. 76, could be applied to any of thefeedthrough capacitors previously described herein.

FIG. 77 is generally taken from FIG. 3 of U.S. Pat. No. 6,008,980, thecontents of which are incorporated herein fully by reference. FIG. 77shows two and three part pins in accordance with the present invention.As previously taught in the present invention, on the left side, thebody fluid side leadwire 118 is co-brazed 138 to device side leadwire117. At the same time, the gold braze 140, between the ferrule 122 andthe hermetic seal insulator, would be formed. Referring once again toFIG. 77, the right-hand side illustrates another alternative of thepresent invention wherein, there is body fluid side leadwire 118 of adifferent material than short pin 117 and then on the device side, thereis a relatively low cost leadwire 118′. On the right-hand side, in agold brazing operation, pins 118 and 117 are co-brazed within thehermetic seal insulator 188. In accordance with the present invention,these two lead segments 117 and 118 could be pre-welded 424 as shown. Inthis case, the low cost leadwire 118 is then inserted into the deviceside along with solder or thermal-setting conductive adhesive 410, whichforms a mechanical and electrical connection between the lead segment117 and leadwire 118′. In general, in accordance with the presentinvention, leadwire 118 could be of biocompatible low cost material onthe body fluid side, such as tantalum, niobium or the like. The shortpin 117 would generally be of platinum or palladium. Leadwire 118′ wouldgenerally be of a tinned copper or other low cost leadwire as previouslydescribed.

Referring once again to FIG. 77, it will be appreciated that thedielectric body 188 is the same throughout. The inventors havediscovered through extensive research and development, that it is notpossible to build the assembly illustrated in FIG. 77 with high kdielectric (ceramics having a dielectric constant of above approximately2000). The reason for this is such dielectrics are mechanically weak andthe gold brazing 140 always induced fractures within the insulatorstructure 188. One could easily build this structure, as shown in FIG.77, with an alumina ceramic, which has a very low k. The problem withthis is the resulting capacitance value, from the electrode plates, asshown, would be relatively low (too low for effective EMI filtering ofpacemakers and implantable defibrillators). The inventors contemplatethat a medium k dielectric could be developed with a k between 200 and1000 that would allow for the co-brazing 140 and still provide a highenough dielectric constant to achieve the required capacitance value.Accordingly, the teachings of U.S. Pat. No. 6,008,980 may be realizablein accordance with the present invention. The use of primary ceramiccapacitor EMI filters having a k less than 1000, is more thoroughlydescribed in U.S. Patent Publication 2015/0217111, the contents of whichare fully incorporated herein.

Although several embodiments have been described in detail for purposesof illustration, various modifications may be made to each withoutdeparting from the scope and spirit of the invention. Additionally, itis to be understood that any of the features taught herein could beapplied to any of the embodiments taught herein. Accordingly, theinvention is not to be limited, except as by the appended claims.

What is claimed is:
 1. A feedthrough subassembly attachable to an activeimplantable medical device, the feedthrough subassembly comprising: a) aferrule, comprising a conductive ferrule body defined as having a firstferrule side opposite a second ferrule side and defining a ferruleopening between and through the first and second ferrule sides; b) aninsulator substrate assembly comprising: i) an insulator body defined ashaving a first insulator side opposite a second insulator side, thefirst insulator side and second insulator side separated and connectedby at least one outside surface, wherein insulator body is at leastpartially disposed within the ferrule opening; ii) at least one via holedisposed through the insulator body extending from the first insulatorside to the second insulator side; iii) an internal metallization formedat least partially on an inside of the at least one via hole; iv) afirst conductive leadwire having a first leadwire first end at leastpartially disposed within the at least one via hole and having a firstleadwire second end disposed past the first insulator side; v) a secondconductive leadwire which is not of the same material as the firstleadwire, the second leadwire having a second leadwire first end atleast partially disposed within the at least one via hole and having asecond leadwire second end disposed past the second insulator side; vi)wherein the first leadwire first end is disposed at or adjacent to thesecond leadwire first end; vii) a first braze contacting the firstleadwire first end, the second leadwire first end and the internalmetallization, the first braze forming a first hermetic seal separatingthe first insulator side from the second insulator side; and ix) anexternal metallization disposed at least partially on the at least oneoutside surface of the insulator body, x) wherein the insulator body isat least partially disposed within the ferrule opening; c) a secondbraze at least partially contacting the external metallization of theinsulator body and the conductive ferrule body to thereby form a secondhermetic seal at the ferrule opening.
 2. The feedthrough subassembly ofclaim 1, further including a feedthrough filter capacitor disposed onthe second insulator side, the feedthrough filter capacitor comprising:a) at least one active electrode plate disposed parallel and spaced fromat least one ground electrode plate, wherein the plates are disposedwithin a capacitor dielectric; b) a first passageway disposed throughthe capacitor dielectric; c) a capacitor internal metallization disposedwithin the first passageway electrically connected to the at least oneactive electrode plate and in non-conductive relation with the at leastone ground electrode plate; and d) a capacitor external metallizationdisposed on an outside surface of the capacitor dielectric andelectrically connected to the at least one ground electrode plate and innon-conductive relation with the at least one active electrode plate. 3.The feedthrough subassembly of claim 2, further including a thirdconductive leadwire having a third leadwire first end at least partiallydisposed within the first passageway of the feedthrough filter capacitorand having a third leadwire second end outwardly beyond the feedthroughfilter capacitor, wherein the second leadwire second end is at leastpartially disposed within the first passageway of the feedthrough filtercapacitor, and wherein the second leadwire second end is at or adjacentto the third leadwire first end.
 4. The feedthrough subassembly of claim3, further including a first electrically conductive material forming atleast a three-way electrical connection electrically connecting thesecond leadwire second end, the third leadwire first end and thecapacitor internal metallization.
 5. The feedthrough subassembly ofclaim 4, wherein the first electrically conductive material is selectedfrom the group consisting of a solder, a solder BGA, a solder paste, anepoxy, and a polyimide.
 6. The feedthrough subassembly of claim 4,including a second electrically conductive material electricallyconnecting the capacitor external metallization to the ferrule and/or tothe second braze.
 7. The feedthrough subassembly of claim 1, includingat least one internal ground plate disposed within the insulator body,the internal ground plate electrically connecting the internalmetallization on the inside of the at least one via hole to the externalmetallization on the at least one outside surface of the insulator body.8. The feedthrough subassembly of claim 1, wherein the first braze andsecond braze are connected by a braze channel.
 9. The feedthroughsubassembly of claim 1, including a conductive clip electrically coupledbetween and to the second conductive leadwire and the ferrule.
 10. Thefeedthrough subassembly of claim 1, wherein the ferrule includes aconductive peninsula extending at least partially into the ferruleopening, and wherein the first braze electrically couples the secondleadwire to the conductive peninsula.
 11. The feedthrough subassembly ofclaim 1, further including a chip capacitor disposed on the secondinsulator side, the chip capacitor comprising: a) at least one activeelectrode plate disposed parallel and spaced from at least one groundelectrode plate, wherein the plates are disposed within a capacitordielectric; b) an active capacitor metallization electrically connectedto the at least one active electrode plate and in non-conductiverelation with the at least one ground electrode plate; and c) a groundcapacitor metallization electrically connected to the at least oneground electrode plate and in non-conductive relation with the at leastone active electrode plate.
 12. The feedthrough subassembly of claim 11,further including a first electrically conductive material electricallycoupling the active capacitor metallization to the second conductiveleadwire.
 13. The feedthrough subassembly of claim 12, further includinga second electrically conductive material electrically coupling theground capacitor metallization to the ferrule and/or the second goldbraze.
 14. The feedthrough subassembly of claim 13, wherein the chipcapacitor is attached to the insulator body.
 15. The feedthroughsubassembly of claim 13, wherein the chip capacitor is attached to acircuit board, and wherein the circuit board is attached to theinsulator body.
 16. The feedthrough subassembly of claim 12, furtherincluding an oxide-resistant metal addition, wherein a secondelectrically conductive material electrically couples the groundcapacitor metallization to the oxide resistant metal addition, andwherein a third electrically conductive material electrically connectsthe oxide-resistant metal addition to the ferrule or wherein theoxide-resistant metal addition is welded to the ferrule.
 17. Thefeedthrough subassembly of claim 1, wherein the second conductiveleadwire comprises platinum or palladium.
 18. The feedthroughsubassembly of claim 17, wherein the first conductive leadwire comprisesniobium or tantalum.
 19. The feedthrough subassembly of claim 1, whereinthe first braze and second braze each comprise a gold braze.
 20. Thefeedthrough subassembly of claim 19, wherein the first braze is disposedat or adjacent to the second insulator side, but does not extend to thefirst insulator side.
 21. The feedthrough subassembly of claim 19,wherein the first braze is disposed at or adjacent to the firstinsulator side, but does not extend to the second insulator side. 22.The feedthrough subassembly of claim 1, wherein the third leadwire firstend is pre-tinned.
 23. The feedthrough subassembly of claim 1, whereinthe first and second hermetic seals have a leak rate that is not greaterthan 1×10⁻⁷ std cc He/sec.
 24. The feedthrough subassembly of claim 1,wherein the external metallization disposed on the at least one outsidesurface of the insulator body comprises an adhesion metallization and awetting metallization, and wherein the adhesion metallization isdisposed at least partially on the at least one outside surface of theinsulator body and wherein the wetting metallization is disposed on theadhesion metallization.
 25. The feedthrough subassembly of claim 2,wherein an insulative washer is disposed between the insulator substrateassembly and the feedthrough filter capacitor.
 26. The feedthroughsubassembly of claim 1, wherein the ferrule is configured to be joinedto an AIMD housing by a laser weld or braze.
 27. The feedthroughsubassembly of claim 1, wherein the ferrule is formed from and as acontinuous part of an AIMD housing.
 28. The feedthrough subassembly ofclaim 1, wherein the first insulator side is a body fluid side and thesecond insulator side is a device side.
 29. An insulative feedthroughthat is configured to attachable to an active implantable medicaldevice, the insulative feedthrough comprising: a) a feedthrough bodycomprising a material which is both electrically insulative andbiocompatible, wherein the feedthrough body has a body fluid side from adevice side; b) a passageway disposed through the feedthrough bodyextending from the body fluid side to the device side; c) a compositeconductor at least partially disposed within the passageway, thecomposite conductor comprising a body fluid side metallic wireelectrically conductive to a device side metallic wire, i) wherein thebody fluid side metallic wire extends from a first end disposed insidethe passageway to a second end on the body fluid side; ii) wherein thedevice side metallic wire extends from a first end disposed inside thepassageway to a second end on the device side; iii) wherein the bodyfluid side metallic wire is hermetically sealed to the feedthrough body;iv) wherein the body fluid side metallic wire is biocompatible; and v)wherein the body fluid side metallic wire is not the same material asthe device side metallic wire.
 30. The insulative feedthrough of claim29, including a ferrule made from an electrically conductive material,the ferrule configured to be hermetically sealed to a housing of animplantable medical device, wherein the ferrule defines a ferruleopening and the feedthrough body is hermetically sealed to the ferruleclosing the ferrule opening.
 31. The insulative feedthrough of claim 30,wherein the ferrule comprises titanium.
 32. The insulative feedthroughof claim 31, wherein the hermetic seal between the ferrule and thefeedthrough body comprises an adhesion layer disposed on an outsidesurface of the feedthrough body, a wetting layer disposed on theadhesion layer, and a gold braze hermetically sealing the wetting layerto the ferrule.
 33. The insulative feedthrough of claim 32, wherein theferrule opening defines an inner ferrule surface, and wherein thefeedthrough body is at least partially disposed within ferrule openingand hermetically sealed by the gold braze to the ferrule inner surface.34. The insulative feedthrough of claim 29, wherein the device sidemetallic wire is not biocompatible.
 35. The insulative feedthrough ofclaim 29, wherein the body fluid side metallic wire comprises platinum.36. The insulative feedthrough of claim 35, wherein the body fluid sidemetallic wire comprising platinum does not include iridium.
 37. Theinsulative feedthrough of claim 29, wherein the second end of the bodyfluid side metallic wire extends outwardly beyond the feedthrough bodyon the body fluid side.
 38. The insulative feedthrough of claim 29,wherein the second end of the device side metallic wire extendsoutwardly beyond the feedthrough body on the device side.
 39. Theinsulative feedthrough of claim 29, wherein the second end of the bodyfluid side metallic wire is aligned with a body fluid side surface ofthe feedthrough body.
 40. The insulative feedthrough of claim 29,wherein the second end of the device side metallic wire is aligned witha device side surface of the feedthrough body.
 41. The insulativefeedthrough of claim 29, wherein the second end of the body fluid sidemetallic wire is recessed inwardly from a body fluid side surface of thefeedthrough body.
 42. The insulative feedthrough of claim 29, whereinthe second end of the device side metallic wire is recessed inwardlyfrom a device side surface of the feedthrough body.
 43. The insulativefeedthrough of claim 29, wherein the first end of the body fluid sidemetallic wire is soldered or welded to the first end of the device sidemetallic wire.
 44. The insulative feedthrough of claim 29, wherein thehermetic seal between the body fluid side metallic wire and thefeedthrough body comprises an adhesion layer disposed on an insidesurface of the passageway, a wetting layer disposed on the adhesionlayer, and a gold braze hermetically sealing the wetting layer to thebody fluid side metallic wire.
 45. The insulative feedthrough of claim44, wherein the gold braze is connected to the device side metallicwire.
 46. The insulative feedthrough of claim 29, further including acapacitor disposed on the device side of the feedthrough body, whereinthe capacitor comprises at least one active electrode plate and at leastone ground electrode plate disposed within a capacitor dielectric, andwherein an active metallization is electrically connected to the atleast one active electrode plate and a ground metallization iselectrically connected to the at least one ground electrode plate. 47.The insulative feedthrough of claim 46, wherein the active metallizationis in electrical communication with the device side metallic wire, andwherein the ground metallization is in electrical communication with theferrule.
 48. The insulative feedthrough of claim 47, wherein thecapacitor is a chip capacitor.
 49. The insulative feedthrough of claim48, wherein the chip capacitor is mounted to the feedthrough body. 50.The insulative feedthrough of claim 48, wherein the chip capacitor ismounted to a circuit board, and wherein the circuit board is mounted tothe feedthrough body.
 51. The insulative feedthrough of claim 47,wherein the capacitor is a feedthrough capacitor.
 52. The insulativefeedthrough of claim 51, wherein the feedthrough capacitor is mounted toan adhesive washer and the adhesive washer is mounted to the feedthroughbody.
 53. The insulative feedthrough of claim 52, wherein the second endof the device side metallic wire extends outwardly beyond thefeedthrough body on the device side and is disposed within a metallizedvia formed through the feedthrough capacitor, and wherein themetallization of the metallized via comprises the active endmetallization.
 54. The insulative feedthrough of claim 53, including athird wire disposed on the device side and extending at least partiallyinto the metallized via of the capacitor.
 55. The insulative feedthroughof claim 54, including a conductive material electrically connected tothe second end of the device side metallic wire, to the third wire, andto the active metallization of the capacitor.
 56. The insulativefeedthrough of claim 30, further including an internally groundedcapacitor disposed on the device side of the feedthrough body, whereinthe capacitor comprises at least one active electrode plate and at leastone ground electrode plate disposed within a capacitor dielectric, andwherein an active end metallization is electrically connected to the atleast one active electrode plate and a ground end metallization iselectrically connected to the at least one ground electrode plate,wherein the active end metallization is formed within an active viadisposed through the capacitor dielectric and the ground endmetallization is formed within a ground via disposed through thecapacitor, wherein the capacitor does not have an external metallizationon an outside surface of the capacitor dielectric and the groundelectrode plate does not extend to the outside surface of the capacitor.57. The insulative feedthrough of claim 56, wherein the feedthrough bodycomprises a conductive pathway in electrical communication with theferrule on one end of the conductive pathway and in electricalcommunication with the ground metallization on the other end of theelectrical pathway.
 58. The insulative feedthrough of claim 57, whereinthe conductive pathway comprises a gold braze.
 59. The insulativefeedthrough of claim 58, wherein the gold braze also hermetically sealsthe feedthrough body to the ferrule.
 60. The insulative feedthrough ofclaim 59, further including a conductive pin in electrical communicationwith the ground metallization on one end of the conductive pin and inelectrical communication with the gold braze on the other end of theconductive pin.
 61. The insulative feedthrough of claim 57, wherein theconductive pathway comprises at least one conductive grounding layerdisposed within the feedthrough body.
 62. The insulative feedthrough ofclaim 61, further including a conductive pin in electrical communicationwith the ground metallization on one end of the conductive pin and inelectrical communication with the conductive grounding layer on theother end of the conductive pin.
 63. The insulative feedthrough of claim56, wherein the ferrule includes an extension extending into the ferruleopening, and wherein a conductive wire is electrically connected to theferrule extension and also electrically connected to the groundmetallization of the internally grounded capacitor.
 64. The insulativefeedthrough of claim 29, comprising: a) a ferrule made from a conductivematerial, the ferrule configured to be hermetically sealed to a housingof the implantable medical device, wherein the ferrule defines a ferruleopening and the feedthrough body is hermetically sealed to the ferruleclosing the ferrule opening; b) a feedthrough capacitor disposed on thedevice side of the feedthrough body, wherein the feedthrough capacitorcomprises at least one active electrode plate and at least one groundelectrode plate disposed within a capacitor dielectric, and wherein anactive metallization is electrically connected to the at least oneactive electrode plate and a ground metallization is electricallyconnected to the at least one ground electrode plate; c) a gold brazeattached to the ferrule on the device side; and d) an electricallyconductive fill connecting the ground end metallization to the goldbraze.
 65. The insulative feedthrough of claim 30, wherein thefeedthrough body comprises a glass insulator, wherein the hermetic sealbetween the feedthrough body and the ferrule is characterized as havingbeen formed at the same time as the hermetic seal between the compositeconductor and the feedthrough body.
 66. The insulative feedthrough ofclaim 64, including an alumina washer disposed over the feedthrough bodyon the body fluid side.
 67. An insulator substrate assembly, comprising:a) an insulator body configured to be attachable to a ferrule or ahousing of an active implantable medical device, the insulator bodydefined as having a first insulator side opposite a second insulatorside, the first insulator side and second insulator side separated andconnected by at least one outside surface; b) at least one via holedisposed through the insulator body extending from the first insulatorside to the second insulator side; c) a first conductive leadwire havinga first leadwire first end at least partially disposed within the atleast one via hole and having a first leadwire second end disposed at orextending outwardly beyond the first insulator side; d) a secondconductive leadwire having a second leadwire first end at leastpartially disposed within the at least one via hole and having a secondleadwire second end disposed at or extending outwardly beyond the secondinsulator side, wherein the first leadwire is not the same material asthe second leadwire, e) wherein the first leadwire first end is disposedat or adjacent to the second leadwire first end, f) wherein the firstleadwire and second leadwire are in electrical communication with eachother, and g) wherein at least the first leadwire is hermetically sealedwithin the at least one via hole to the insulator body.